NEW YORK (AP) — If there is a “best-of” list for music this year, it’s a safe bet to put Adele on top. Billboard has declared her the No. 1 artist of 2011. Rihanna was No. 2, followed by Katy Perry, Lady Gaga and Lil Wayne. The list, announced Friday, takes into account album sales, charting singles, radio airplay and other factors.