Welcome to autumn! Summer won’t be over for another three weeks, calendrically speaking — but when it comes to music sales, those warm-weather doldrums just ended with a bang. No less than half of the Top 20 on the new Billboard 200 albums chart are new releases, a welcome change from the last month or so of just a few debuts per week.

Leading the pack by a healthy margin at No. 1 is Colbie Caillat, whose aptly titled Breakthrough sold 106,000 copies, according to Nielsen SoundScan. That’s more than twice what her debut managed in its first week back in 2007, and it’s nearly 40,000 more than this week’s No. 2 album: Awake, from Christian metal quartet Skillet, who fried up 68,000 in sales. Miley Cyrus’ Time of Our Lives EP fills out the Top 3 with 64,000 sold, joining her Hannah Montana the Movie soundtrack on the chart.

After that — take a deep breath — comes Imogen Heap’s Ellipse at No. 5 with 48,000; NOW That’s What I Call Country Vol. 2 (featuring hits by Keith Urban, Taylor Swift, Darius Rucker, and more) at No. 10 with 33,000; LeToya’s Lady Love at No. 12 with 33,000; Arctic Monkeys’ Humbug at No. 15 with 28,000; Ingrid Michaelson’s Everybody at No. 18 with 23,000; Matisyahu’s Light at No. 19 with 22,000; and, finally, Christian rock band Needtobreathe’s The Outsiders at No. 20 with 21,000.

Whew! Any surprises among all those fresh faces on the chart? Who do you think has the legs to stick around for next week? Does anyone have a shot at upsetting Whitney Houston’s I Look to You, which went on sale this Monday?

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