This graph (demographers normally call it as the population pyramid) compares the age-sex distribution of centenarians between different countries. The initial purpose of this graph is to show the accuracy of age-reporting for China as compared to Sweden and Japan, the two countries with highest accurate in age-report in the current world, and some selected developed countries.
It has various applications. Using this type of pyramid, one can always compare different age-sex distributions either in numbers or percentage across different populations and periods to examine the age-sex structure change.
This type of graph is provided by Danan Gu, Ph.D., Research Scientist at Medical Center, Duke University. The data for China is from the Chinese Longitudinal Healthy Longevity Survey in the baseline wave in 1998. Data for other countries are from Kannisto-Thatcher Database on Old Age Mortality.