比爾蓋茨：記住這三個數據將理解這個世界

比爾·蓋茨近期表示，記住這三個數據將幫助你理解這個世界。

OurWorldInData.org是我最喜歡的網站之一。這個網站設在牛津大學，利用關於從健康、人口增長到戰爭、環境和能源等方方面面的統計數據，讓你深刻了解世界各地人們的生活條件正在發生怎樣的變化。我邀請了網站創始人——牛津大學的經濟學家麥克斯·羅瑟（Max Roser）——跟大家分享三個所有人都應了解的事實。以下的內容由麥克斯撰寫。

在過去的幾年裡，通過快速的在線搜索，人們很容易就能找到全球發展的許多重要數據。由於現在找到所需信息變得如此容易，很多人認為記住這些數據沒有意義。他們說：「需要的時候再查閱下就好了！」

我不同意這種說法。是的，對一些細節，你需要的時候再去搜索數據的確合情合理。但是對於宏大的全球發展問題，了解目前人們生活條件的基本數據，以及過去幾十年中我們看到的變化趨勢非常重要。了解這些全球變化的事實，能給你提供每日新聞的背景，還能讓你真正理解你所掌握的新信息。而且，這也必定是政治辯論的基礎，只有這樣我們才能去討論，作為一個社會整體我們應該做什麼以及不應該做什麼。

因此，我列了一個簡短的清單，包含三條我想記住的關於全球生活條件的事實。其中每一條都描述了當前的情況和變化趨勢。

事實1：自1960年以來，兒童死亡人數已從每年2000萬人下降到每年600萬人

想像一下看著自己的孩子死去會多麼痛苦。

然後試想一下，每分鐘這一情況就會發生在大約11位父母身上。這是平均每分鐘的五歲以下兒童死亡數字。24小時內的每分鐘都有11名兒童死亡，那每天死亡人數累計為15500人，即每年有560萬名兒童死亡。

我們必須接受這一點嗎？世界就是這樣的嗎？

顯然不是。我們有很強的能力去推動積極的改變。請看下面的圖表。聯合國數據告訴我們，現在每年有560萬兒童死亡；同時數據也向我們表明，在20世紀50和60年代，世界每年兒童死亡的數據為2000萬。

我們很難看到當前世界進步的一個關鍵原因是，我們不知道過去有多糟糕。

這兩種說法都是對的：這個世界比過去要好得多，這個世界仍然很糟糕。

為了記住這一情況，我需要同時知道兩邊的數據：當有人說我們可以坐下來放鬆一下，因為這個世界比過去好得多，我會指出每分鐘仍有11個孩子死去的事實。我們不能接受現在這樣一個世界。而當我在這場悲劇面前感到絕望時，我會記得在過去的五十年里，我們把每年兒童死亡的數量從2000萬減少到了560萬。

因此，我記得目前的兒童死亡率以及我們看到的變化趨勢：兒童死亡人數正在下降，50年前兒童死亡人數是現在的3.5倍。但兒童死亡現象仍然非常普遍，平均每分鐘都有11名兒童夭折。

事實2：自1960年以來，生育率下降了一半

全球人口的迅速增長並非不可阻擋。我們之所以知道這一點，是因為在過去幾十年中，我們已經看到全球人口變化將終結人口的快速增長。讓我們來看看數據。

下面的圖表顯示了認識世界人口增長情況的關鍵統計指標——全球生育率，即世界上每名婦女的平均子女人數。當生育率接近2，那麼每對夫婦平均被大約兩個孩子取代，人口增長緩慢。但是直到20世紀60年代末，每個婦女平均有5個以上的孩子。如此高的生育率，人口增長就很快。當時，每年的世界人口增長率為2%。

避孕工具的供應使得父母想要多少孩子就生多少孩子。這個數字隨著人們收入的增加而變化。從幾十年的人口統計學研究中，我們了解到女性在獲得更好的教育和更好的就業機會時會決定少生孩子。我們還知道，當兒童死亡率下降，家庭不必擔心他們的孩子會死亡時，會從一開始就決定少生孩子。

婦女生活條件和兒童健康水平的提高，促使世界各地的生育率迅速下降。事實上，在過去的50年里，全球生育率已經下降了一半，從每個婦女生育超過5個孩子減少為不到2.5個孩子。在過去的50年里，世界人口增長率也下降了一半，僅略高於1%。

我所記住的人口增長統計數據告訴我，人口的快速增長將在本世紀內結束。在過去50年中，全球生育率已從每名婦女生育5個子女降至每名婦女不足2.5個子女。五十年來，生育率已經減半。

事實3：1990至2015年間，每天有13.7萬人脫離極端貧困

生活在貧困中意味著生活中許多最重要的東西都遙不可及。貧困人口往往缺乏體面的住房和基本的醫療服務，並且常常買不起足夠的食物。

每天必須靠不到1.90國際元（international-dollar，一種可以校正國家之間價格差異和通貨膨脹的假定貨幣）收入生活的人們，被認為處於「極端貧困」狀態。

對於貧困的這一定義，用「極端貧困」這個詞來概括顯然非常恰當:這確實是一條非常低的貧困線。

當你問人們世界是否在對抗極端貧困方面獲得了進展時，我們大多數人相信情況正在惡化，相信生活在極端貧困中的世界人口數量正在上升。

但事實恰恰相反，極端貧困人口的數量和比例都在下降:

1990年，18.6億人每天收入不足1.9國際元，佔世界人口比例超過三分之一。25年後，極端貧困人口減少了一半以上，降至7.06億，也就是十個人中只有一個。

這是一個非常巨大的轉變。這意味著過去25年中，平均每一天生活在極端貧困中的人數都比前一天減少了13.7萬人。過去25年里，每一天都原本可以有這樣的新聞標題：「從昨天到今天，極端貧困人口減少了13.7萬人。」

這就是我記得的統計數字：今天，每十個人中就有一個生活在極端貧困之中，全球範圍內有7.06億。數量之多令人無法接受。但我們也應知道，趨勢正在朝著好的方向發展。極端貧困人口的數量正在下降。終結極端貧困是可能的。

記住這三個關於世界的事實讓我想起了為什麼我認為參與全球發展很重要。關於世界現狀的統計數字表明，我們不能滿足於世界目前的狀況，但是關於全球變化的統計數字告訴我們，創造一個更美好的世界是可能的。兒童死亡人數正在下降，人口迅速增長的挑戰不會無限期地持續，極端貧困人口的數量正在減少。

讓我們繼續朝著這個方向前進，過去的成功應該鼓舞著我們為取得更多進步而努力。

Memorizing these three statistics will help you understand the world

One of my favorite websites is OurWorldInData.org. Based at the University of Oxford, it uses statistics—on everything from health and population growth to war, the environment, and energy—to give you phenomenal insight into how living conditions are changing around the world. I asked its founder, Oxford economist Max Roser, to share three facts from the site that everyone should know. Here』s what Max had to say.

–Bill Gates

In the past few years, it has become easy to find many of the important statistics on global development with a quick online search. And since it is now so easy to find the information you need, many argue that it doesn』t make sense to actually remember these statistics. 『Just look them up when you need them!』 they say.

I disagree with this. Yes, for some details, it makes sense to just search for them when you need them. But for the large global developments, it is important to know some basic statistics that describe living conditions currently and the direction of change that we have seen over the past few decades. Knowing the facts on global changes gives you the context for the daily news and allows you to make sense of new information that you learn. And it must be the basis for political debate, so that we can discuss what we should and shouldn』t do as a society.

And so I compiled a short list of three facts about global living conditions that I want to remember. Each of them describes the current situation and the direction of change.

Fact #1: Since 1960, child deaths have plummeted from 20 million a year to 6 million a year.

Imagine how awful it must be to see your child die.

Then consider that every minute this happens to about 11 parents. This is the number of children, younger than five years of age, who die—on average—every single minute. Eleven deaths every minute for 24 hours add up to 15,500 deaths per day, or 5.6 million deaths per year.

Do we just have to accept that? Is that just how the world is?

Clearly no. We are very much able to drive positive change. Look at the chart below. The same UN data that shows us that 5.6 million are dying today also shows us that in the 1950s and 60s the world saw around 20 million children dying every year.

One key reason why we struggle to see progress in the world today is that we do not know how very bad the past was.

Both are true at the same time: The world is much better than in the past and it is still awful.

To bring this to mind I need to know both statistics: When someone says we can sit back and relax because the world is in a much better place, I point out that 11 children are still dying every minute. We cannot accept the world as it is today. And when I feel hopeless in the face of this tragedy, I remember that we reduced annual child deaths from 20 million to 5.6 million in the last fifty years.

So I am remembering the current extent of child mortality and the direction of change that we have seen: The number of child deaths is falling; there were 3.5-times as many child deaths 50 years ago. But child deaths are still extremely common; 11 children are dying every minute.

Fact #2: Since 1960, the fertility rate has fallen by half.

The chart below shows the key statistic to understand about world population growth: the global fertility rate—the average number of children per woman in the world. When the fertility rate is close to 2 children per woman, so that every couple is on average replaced by about two children, population growth is slow. But until the late 1960s, each woman had on average more than 5 children, and at such high fertility rates, population growth is fast. At that time the world population increased by 2 percent every year.

The availability of contraceptives allows parents to have only as many children as they want. And that number changes as people』s income goes up. From decades of demographic research, we know that women decide to have fewer children as they get access to better education and better opportunities in the job market. We also know that when child mortality falls, so that families do not need to fear that their children will die, they consequently decide to have fewer children in the first place.

Improvements in conditions for women and the health of children have driven a rapid reduction in fertility rates across the world. In fact, the global fertility rate has halved in the last 50 years, from more than 5 children per woman to fewer than 2.5 children. The world population growth rate has also halved in the last 50 years and is just above 1 percent.

The statistic that I remember on population growth is the one that tells me that rapid population growth is coming to an end in this century. In the last 50 years the global fertility rate has fallen from 5 children per woman to less than 2.5 children per woman. In fifty years the fertility rate has halved.

Fact #3: 137,000 people escaped extreme poverty every day between 1990 and 2015.

Living in poverty means that many of the most essential things in life are out of reach. People in poverty tend to lack decent shelter and basic healthcare, and they often struggle to afford adequate food supplies.

People are considered to live in『extreme poverty』if they have to get by on less than 1.90 international-dollars per day, which is a currency that corrects for price differences between countries and inflation.

In this definition of poverty, the term extreme poverty is clearly appropriate: this is a very low poverty line.

When you ask people whether the world is making progress against extreme poverty, the majority of us believe things are getting worse—that the number of people in extreme poverty in the world is rising.

The opposite is true. Both the number and the share of people in extreme poverty is falling:

In 1990, 1.86 billion people were living on less than 1.90 international-$ per day—more than every third person in the world. Twenty-five years later, the number of people living in extreme poverty has more than halved to 706 million, every tenth person.

This is a very large transformation. It means that, on average, every day for the past 25 years 137,000 fewer people were living in extreme poverty than the day before. On every day in the last 25 years there could have been a newspaper headline reading,「The number of people in extreme poverty fell by 137,000 since yesterday.」

This is the statistic I remember: Today every 10th person is living in extreme poverty—706 million people. An unacceptably large number of people. But we should also know that the trend is moving in the right direction. The number of people in extreme poverty is falling. It is possible to end extreme poverty.

Remembering these facts about the world brings to mind why I think it is important to get engaged in global development. The statistics on the current state of the world make clear that we cannot be complacent about the world as it is today. Especially because progress is uneven, and in sub-Saharan Africa progress has been slower, but is not absent. The statistics on global change over time tell us that it is possible to work for a better world. The number of child deaths is dropping. The challenges of rapid population growth will not continue indefinitely. And the number of people in extreme poverty is falling.

Let』s continue in this direction. Our past successes should encourage us to work for more progress.

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