Another reason for Pharrell Williams to be happy: his signature song was the most-played track of the decade in the U.K.Pharrell’s “Happy” came out on top of a new chart, published this week by the BBC Radio 2 based on exclusive data from Phonographic Performance Ltd. (PPL), with hits by Adele and Maroon 5 close behind.Adele is the only female in the top 10 as “Rolling In The Deep,” lifted from her best-selling 2010 album 21, comes in at No.