The graph gives information about the number cases of X disease in Someland between 1960 to 1995.
It is clear that Someland experienced considerable changes in the incidence of X disease. The number of people got this disease peaked in 1975s.
In 1960, there was about 100 cases of X disease. Over the course of 10 years staring 1965, this figure increased drammatically. After since, it peaked and stayed steady at 500 cases from 1975 to1980.
From 1980, the incidence of the patients decresed to about 350 cases. It continued to decrese steeply for the next 5 years. It is also projected to decline in the next years.