The given line chart shows the information about the weekly number of iTunes purchased songs. To begin with, we can see that in the first 15 weeks, the sales number is being less than 10 million. According to the graph, the growth of the sales keep flat from week 10 to week 45, with a growth from 10 million to 50 million. Last but not the least, the sales figure increased dramatically after week 45 and reached a sales figure of more 1000 million. In conclusion, the number of purchased songs in iTunes has continuously increased with an increasing growth rate.