It's the number of people on each income, from one dollar a day —  See, there was one hump here, around one dollar a day, and then there was one hump here somewhere between 10 and 100 dollars.
是人均收入的数值 从每天一美元  看 这里有一个高峰 在每天一美元左右 然后这里还有一个高峰 大约在10到100美元之间