Rihanna? Justin? My data was confusing at first

In 2012, while travelling on plane from Edmonton, Canada to Vancouver, BC, a thought crossed my mind ... who is the most popular music artist in the world. By popularity, I meant, the one whose songs was the most shared on popular sites such as FB, Twitter and Youtube. When I got to Vancouver, I set up a crawler and gathered over 39000 artist names and over 400,000 song titles. Then for each artist + song name, I check the social sites for the most shares / comments / recommendations / tweets etc., as a proxy for popularity or social engagement. Prior to adding up the numbers I was expecting Rihanna or Justin Bieber to be on the top of the list. I was also mindful of problems with the data, such as songs released prior to the popularity of social networks, growth rate of social networks vs. accumulated likes / shares and many more. Anyways, considering the rough data I had, when I added up the #s, Eminem was on top. I was confused by the data. Why Eminem ... So anyways, I decided to dig further and to my surprise, Eminem I found out that he is very smart in how he markets his songs. Basically, he generates multiple waves of popularity for his music .. First the song comes out .. which is cool. Then when it cools off, the same song gets used for a movie sound track ... and eventually, it gets used as a sound track for a video game. So there u go ... when I run my data, Eminem was the King of social networks in 2012 :) Thanks for reading.