It’s the year of the ladies so far: The biggest selling album for the first half of 2011 belongs to Adele and the best selling digital song to Katy Perry.

Adele’s “21” has sold 2.5 million copies since its Feb. 22 release in the U.S., according to Nielsen SoundScan via Billboard. The second best-selling album so far belongs to Lady Gaga. “Born This Way,” which has shifted 1.5 million copies since it came out May 23. They are the only two albums released in 2011 to surpass 1 million in sales.

Coming in at No. 3 is Mumford & Sons’ “Sigh No More,” which has sold 982,000 since Jan. 1 (for a cumulative tally of 1.6 million since its release 71 weeks ago.  No. 4 is Jason Aldean’s “My Kinda Party” at 763,000 (1.4 million total in 34 weeks).

So how does this compare to the first half of 2010? It’s not much, but album sales for the first half are up 1%  over the first half of 2010 for a total of 155.46 million. More significantly, it marks the first time since 2004 that album sales have increased.

On the singles front, Perry’s “E.T.” featuring Kanye West has sold 4.12 million copies. It is one of two singles to hit the 4 million mark: Adele’s “Rolling in the Deep,” which spent 7 weeks at No. 1 on the Billboard Hot 100, has sold 4.089 million digital downloads.

Last year, no single had moved that many copies yet: the leader was Train’s “Hey, Soul Sister” at 3.38 million. So far this year 52 songs have sold at least 1 million downloads compared to 39 at last year’s midway point.  Overall, digital track sales are up 11% over the first half of 2010.