Your approach for this task needs improvement. You need to have an intro, overview and body paras (ideally two paras with details). Let's take your intro;
These pie charts compare the percentage of most popular leisure activities in U.S.A. in years 1999 and 2009. It is clear that walking and jogging together constitute almost 35 % of the leisure activities in these years .
... the purpose of intro is to introduce the image (can be a graph, chart, table, diagram or combination of them) to the reader. You should include time frames if there are any. So, the second part of your intro is not really should not be there and that's why I striked it off.
Then comes the Overview which gives a broad idea about what the image presents. Here you discuss the most obvious trends/ observations. For example;
Soccer had been the most popular leisure activity from 1999 to 2009 and its popularity has grown over the years. Jogging, aerobics, yoga and bicycling had been among the least popular leisure activities.