The average song duration on the Billboard Hot 100 list is currently three minutes and 30 seconds, which is 20 seconds shorter than it was five years ago. But many songs reach much longer careers. Songs have been staying at number one for more recently released products such as Xbox Live and PlayStation Network. These songs typically stay at number one for only weeks or months before being replaced by another song. However, some songs have managed to stay at number one for years such as "We Are One (The World Song)" by The Plastics and "Happy" by Pharrell Williams. In order to keep a song popular, musicians create new versions of it. These remixes are often sold as official merchandise or given away for free with magazines or newspapers. Some musicians have also created covers version of their own songs, which are not considered remixes because these covers are not done by other artists. For example, Elton John has covered "Your Song" multiple times and will always put his name on the cover notes so it is not considered a remix even though other musicians have also sung the song. There are several factors that determine how long a song remains popular. New releases songs tend to replace older ones, and newer songs are usually faster-paced and use more complex music technology.