The given information illustrates the proportion of sold books categories by one bookseller in years of 1972, 1992 and 2012.
Overall, as it can be seen the percentages of adults and children fiction rise sharply while the percentages of other three categories about travel, biography and others fell dramaticly.
In 1972, book types as adult fiction, children fiction and biography had the same percentage of 20% and the quarter of the pie was occupied by the category of others and the last type of book travel took only 15% of the pie. Next, in year 1992 proportion of pie chart changed slightly, the types of book which experienced rise in sales were travel, adults and children fiction. Adults fiction gained 5% percents and overall took 25% of the pie, the proportions of childrens fiction growed to 22% and the sale percentage of travel book types increased to 18%
In 2012, there were a dramatic changes in pie chart, almost all of the book categories went trough a sudden drop exept adult and children fiction. The proportions of adult fiction jumped to 45% and took almost a half of the pie and the percentages of child fiction increased to 25% and took quarter of the pie chart.