Shania Twain has increased her lead as the best-selling country female of all time by 2 million units, according to the RIAA. Twain's "Greatest Hits," her best-of set released in 2004, has now been certified quadruple platinum for sales of four million units. Soundscan reports the album has actually sold 3.7 million copies.

With the latest certification, Twain has now sold 48 million albums in the United States. That places her #6 all-time among females, behind Barbara Streisand, Madonna, Mariah Carey, Whitney Houston and Celine Dion. Reba McEntire is #2 behind Twain for best selling female in country music, with 40.5 million units sold.

Twain's 1997 "Come On Over" album is the best selling country album and best selling female album of all time. It is also the best selling album since 1990, according to Soundscan. It is certified two-time diamond for sales of over 20 million copies. It is estimated that Twain has sold over 70 million records world-wide.

A new studio album is expected from Twain this year.

Labels: Reba McEntire, Shania Twain