Overall, vegetarianism was more popular in the twentieth century than it is now.
I feel you better pay more focus to describe the trend .... Actually, the popularity has first increased, then declined and again on the rise. That's what you should have said in the overview. However, you should not include details in the overview such as figures, data or statistics.
Interestingly , there was a significant fall right after the peak (from 15% to 6%).
... Since this is about report writing, you need to adopt a more formal approach.
Overall, a very good attempt. You display good writing skills :)