There are five questions below，

 In answering these questions, assume that the male and female populations are equal for each of the years shown.

For which of the following years was the difference between the life expectancy at birth for males and the life expectancy at birth for females the least?

The average(arithmetic mean) life expectancy at birth for a person born in 1980 was approximately how many more years than for a person born in 1900?

The life expectancy at birth of a male born in 1900 is closest to what fraction of the life expectancy at birth of a male born in 1980?

Which of the following statements can be inferred from the graph?

Ⅰ For each year shown, the life expectancy at birth was greater for females than it was for males.

Ⅱ The increase in the life expectancy at birth for males was greater from 1940 to 1980 than it was from 1900 to 1940.

Ⅲ For each year shown, the difference between the life expectancy at birth for males and that for females was greater than the corresponding difference in the preceding year shown.

From 1900 to 1980, life expectancy at birth for males increased by approximately what percent?