The pie charts illustrate the percentage of people who use US online music service from five age groups in 2013, 2015, and 2017.
Overall, it is clear that the all age groups changed substantially over the period, especially the users between 10 and 19 years old were the most. The percentage of 40 to 49-year-olds made of the largest portion in 2013 while it changed to 30-39 year olds in 2015. Lastly, the people form 20 to 29 years old accounted for the largest portion in 2017.
Looking at the graph more closely, one can observer that the percentage of 40-49 year olds was the highest percent, 34 percent, in2013, but it decreased to 14 percent by 2017. The age group composed more than 50 years old also dropped steadily to 4 percent in 2017. In contrast, the portion of the users from 10 to 19 years old was 5 percent, with the lowest percent, in 2013 ,but it increased to 24 percent by 2017 so it made of the second largest category. In the case of the 30 to 39-year-olds, although the rates rose from at 31 percent in 2013 to 33 percent in 2015, in 2017 , it shrunk to 24 percent. Meanwhile, the proportion of 20-29 year olds surged continually, reaching at 34 percent by 2017, and then occupied the most area in the chart.