The sales are for albums, though, not singles, and those are domestic sales only. Just FYI, Kelly's album, 'Breakaway', has sold about 13 million copies worldwide as of the latest figures.
According to figures released by Sony Music, Kelly's three albums combined have sold well over 20 million copies worldwide. Her fourth album debuts tomorrow. The first single from it, 'My Life Would Suck Without You', has already gone #1 in the U.S. and UK, and is on its way to double platinum.
The Grammy-winning 'Because of You' is Kelly's biggest worldwide hit in the pop genre, and it even went #1 on the Country radio airplay charts as the first single off Reba McEntire's 'Duets' album. The duet of 'Because of You' with Kelly became Reba's 30th Top-20 country single, peaking at #2 on the Billboard Hot Country Songs chart. It was also her 50th Top 5 single, tying her for the record with Dolly Parton among female country artists.
I don't know if these are the absolute latest figures, since albums can continue to sell for years, but you can find the top-selling American Idol alumni list by domestic sales here.
Among other things, that list clearly shows Clay Aiken's decline across the four albums he's released. His first sold 2,780,000, but his fourth sold only 160,000.
Lastly, like so many other businesses these days, the music industry has been experiencing serious sales declines over the last year or so. Last info I saw was that album sales were down over 8% from the same period last year. U2's new album debuted last week and is on track to be #1 this week with sales of around 400–450K. It is expected to fall off as much as 60% in its second week.
PS: Have you moved yet?