he Adele train just keeps a-rollin’ this week as her “21” album moves back up the Billboard 200(up two spots to No. 2) with a 31% gain (101,000 sold, according to Nielsen SoundScan).

The mega-successful “21” also surpasses 9 million in U.S. sales too, becoming only the 29th album in the SoundScan era (1991-present) to cross the 9 million mark.

An album last reached 9 million a year ago this week (May 15, 2011) when Bob Seger & the Silver Bullet Band’s 1994 set “Greatest Hits” tip-toed past the threshold.

“21” is also spending its 64th consecutive week in the chart’s top 10, tying Paula Abdul’s “Forever Your Girl” for the second longest top 10 run among albums by women. Leading the female pack is Alanis Morissette’s “Jagged Little Pill,” with 72 top 10 weeks. (Among all albums, the soundtrack to “The Sound of Music” has the most weeks in the top 10, with 109.)

Certainly, “21” is performing well beyond even the most optimistic expectations. Last September, after her performance at the MTV Video Music Awards, Adele’s label, Columbia, projected that “21” would sell 4.5 million by the end of 2011 and 5 million-6 million by March 2012. By the time each benchmark rolled around, the album was about 1.5 million-2 million ahead of those forecasts.

As if you need reminding: “21” is clearly in a class all its own. “21” certainly seems poised to reach 10 million in the coming months, even without the singer herself doing much major promotion. She’ll soon be seen in a one-hour NBC primetime special dubbed “Adele Live in London,” which will air June 3.

The broadcast will include highlights of the singer’s 2011 “Live at the Royal Albert Hall” DVD concert and an interview with the network’s Matt Lauer. Meanwhile, “21”‘s current single, “Rumour Has It,” seems to be cooling off at top 40 radio. It holds at No. 8 on the Pop Songs airplay chart (down 236 detections, according to Nielsen BDS), after peaking last week. On the Billboard Hot 100, the song loses its bullet at No. 16 — where it’s been parked for the past three weeks.

On the bright side, the song’s on the Adult Pop Songs and Adult Contemporary airplay charts are still bright. On the former, it gets a backward bullet at No. 3 (down one slot) while on AC it climbs 18-17. “Rumour” is the fourth and final single from “21”. Its first three (“Rolling in the Deep,” “Someone Like You,” “Set Fire to the Rain”) all reached the top two rungs on Pop Songs and No. 1 on the Billboard Hot 100.

After “Rumour” completes its run, let’s hope we can look forward to a new single by Christmas. The singer told NRJ Radio last month that she’ll have “a new song probably coming out at the end of the year.” It may not necessarily be from a new studio album though, as — rumor has it — it could be the theme to the next James Bond film, “Skyfall,” which opens in U.S. theaters on Nov. 9.