As country develops, the inhabitants usually become wealthier - and healthier.
They have better health care, drink cleaner water, and eat better food.
Both men and women can expect to live longer.
For exam, table a shows that in japan the average life expectancy at birth for men is 81.4 year, and for women is 87.5 years.
On the other hand, in a developing country like Zambia, it is just 38.5 for men and 38.5 for women.