Taylor Swift's Speak Now topped the 4 million mark in U.S. sales last week. This week it advances to 4,015,000. All three of Swift's regular studio albums have reached this plateau. Taylor Swift has sold 5,170,000 copies. Fearless has sold 6,507,000. Swift is the first female solo artist to top the 4 million mark with three studio albums in a row in a decade. Britney Spears did it with her first three albums, which were released from 1999 to 2001. Shania Twain did it with three albums in a row released between 1995 and 2002.
Britney's and Shania's album were in a row too.
What the article says is that Taylor is the first female to do it since Britney and Shania did it a decade ago.