1920年开始中国和美国的人口逐渐上升
中国在1935年出生率达到了15%
中国在1940年突然下降到了5%
直到1945年开始直线上升到了20%
美国也在1945年从4%上升到了15%
可以发现1945年开始人口直线上升 小弟不才 只有靠大家了

Since 1920, China and the United States of America 's population increased gradually.China was born in 1935 at a rate of 15%, in 1940 China suddenly dropped to 5%, until 1945, come straight up to the 20% from the 1945. America increased from 4% to 15% in 1945 too.which can be found from the 1945 population began to rise sharply.

China as well as USA had been increasing on population since 1920.
有点像雅思小作文，就当自己练习吧。剩下的吃完饭来搞。。

中国在1935年出生率达到了15%
the birth rate of china reached 15% in 1935
中国在1940年突然下降到了5%
and decreased suddenly to 5% in 1940
直到1945年开始直线上升到了20%
after that the rate began to soar to 20% in 1945
美国也在1945年从4%上升到了15%
the birth rate of USA also increa ascended from 4% to 15%
可以发现1945年开始人口直线上升
It was turned out that the rate began to sheer rise in 1945

China and the United States began in 1920 the population rises gradually
China was born in 1935 at a rate of 15%
In 1940 China suddenly dropped to 5%
Until 1945 come straight up to 20%
The United States in 1945 also increased from 4% to 15%
Can find 1945 population line