the world average life expectancy [has doubled] over the last century. Are you referring to the life expectancy for 20-year-olds? [Edit: I found some data her

the world average life expectancy [has doubled] over the last century. Are you referring to the life expectancy for 20-year-olds? [Edit: I found some data here: http://www.cdc.gov/nchs/fastats/lifexpec.htm http://www.cdc.gov/nchs/fastats/lifexpec.htm http://www.cdc.gov/nchs/data/nvsr/nvsr56/nvsr56_09.pdf http://www.cdc.gov/nchs/data/nvsr/nvsr56/nvsr56_09.pdf 20-year-olds do seem to have benefited quite a bit in the first half of the 20th century. I had assumed that life-expectancy was virtually unchanged across the century, except for that of infants and other under-five-year-olds.]