" Over the past millennium, world population rose nearly 24-fold, per capita income 14-fold, GDP 338-fold. This contrasts sharply with the preceding millennium, when world population grew by only a sixth, and per capita income fell. From the year 1000 to 1820, growth was predominantly extensive. Most of the GDP increase went to accommodate a four-fold increase in population. The advance in per capita income was a slow crawl—the world average increased only by half over a period of eight centuries.

In the year 1000, the average infant could expect to live about 24 years. A third died in the first year of life. Hunger and epidemic disease ravaged the survivors. By 1820, life expectation had risen to 36 years in the west, with only marginal improvement elsewhere.

After 1820, world development became much more dynamic. By 2003, income per head had risen nearly ten-fold, population six-fold. Per capita income rose by 1.2 per cent a year: 24 times as fast as in 1000–1820. Population grew about 1 per cent a year: six times as fast as in 1000–1820. Life expectation increased to 76 years in the west and 63 in the rest of the world. "

― , Contours of the World Economy, 1-2030 AD: Essays in Macro-Economic History