Adele is halfway to achieving a rare US album chart feat after leading all sales in 2012.

The British singer's 21 was last year's (11) bestseller and it's way ahead of the chasing pack at the mid-point of 2012.

Over 5.8 million copies were sold last year and more than half that amount (3.7 million) have been snapped up since the beginning of January.

In fact, Adele's hit album is the only one to have sold over a million copies in 2012, and has more sales in the past six months than the next four releases combined.

Lionel Richie's Tuskegee comes in second with 910,000 sales, while One Direction's Up All Night is third with 900,000.

Whitney Houston's Greatest Hits and the Now 41 compilation round out the mid-year top five.

Meanwhile, the year's bestselling digital download so far is Gotye's Somebody That I Used to Know (5.5 million), which has sold an estimated 500,000 copies more than second placed fun's We Are Young.

Carly Rae Jepsen's Call Me Maybe, Kelly Clarkson's Stronger (What Doesn't Kill You) and Starships by Nicki Minaj round out the top five.