【每日商业图表】 09-12-02 lower fertility is changing the world for the better

夜空星辰

SOMETIME in the next few years (if it hasn’t happened already) the world will reach a milestone: half of humanity will be having only enough children to replace itself. That is, the fertility rate of half the world will be 2.1 or below. This is the “replacement level of fertility”, the magic number that causes a country’s population to slow down and eventually to stabilise. According to the United Nations population division, 2.9 billion people out of a total of 6.5 billion were living in countries at or below this point in 2000-05. The number will rise to 3.4 billion out of 7 billion in the early 2010s and to over 50% in the middle of the next decade. The countries include not only Russia and Japan but Brazil, Indonesia, China and even south India.

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The move to replacement-level fertility is one of the most dramatic social changes in history. It manifested itself in the violent demonstrations by students against their clerical rulers in Iran this year. It almost certainly contributed to the rising numbers of middle-class voters who backed the incumbent governments of Indonesia and India. It shows up in rural Malaysia in richer, emptier villages surrounded by mechanized farms. And everywhere, it is changing traditional family life by enabling women to work and children to be educated. At a time when Malthusian alarms are ringing because of environmental pressures, falling fertility may even provide a measure of reassurance about global population trends.

The fertility rate is a hypothetical, almost conjectural number. It is not the same as the birth rate, which is the number of children born in a year as a share of the total population. Rather, it represents the number of children an average woman is likely to have during her childbearing years, conventionally taken to be 15-49.

If there were no early deaths, the replacement rate would be 2.0 (actually, fractionally higher because fewer girls are born than boys). Two parents are replaced by two children. But a daughter may die before her childbearing years, so the figure has to allow for early mortality. Since child mortality is higher in poor countries, the replacement fertility rate is higher there, too. In rich countries it is about 2.1. In poor ones it can go over 3.0. The global average is 2.33. By about 2020, the global fertility rate will dip below the global replacement rate for the first time.

lxd168

这张图很形象，是在折线图的基础上插入可爱的小孩的图片制作而成的吧。图中的横线是怎么出来的呢？