R&B singer Chris Brown, 19, has been named by Billboard Magazine as 2008s top artist based on a number of factors which include album sales, radio airplay, internet streams and digital downloads.The singer told Billboard in an interview Thursday, Its bigger than what I can ever imagine. Its unexpected totally, so its a surprise.The singer should be thankful due to the number of hits hes had this year which include With You, Forever and the collaboration with American Idol Winner Jordin Sparks on the track No Air.On last month, the multi-talented artist won three awards at the American Music Awards, including artist of the year and most recently he was nominated for two Grammy Awards for the 51st Grammy Awards. The 51st Grammy Awards will take place on February 8, 2009 and will broadcast on CBS at 8PM EST.