System of a Down doubles its pleasure

For the sixth straight week, a new album has taken over the No. 1 spot on the national sales chart. This time it’s by System of a Down, whose “Mezmerize” topped the chart Wednesday after selling 453,000 copies last week, according to Nielsen SoundScan. With the year’s fourth-highest debut, the Los Angeles rock group succeeds the Dave Matthews Band, Nine Inch Nails, Bruce Springsteen, Rob Thomas and Mariah Carey at No. 1.

Country star Toby Keith has the No. 2 album on the new chart with “Honkytonk University,” which sold 283,000 copies. Top 10 debuts were also registered by R&B singer-songwriter Kem (No. 5), a collection of “American Idol” finalists (No. 6) and veteran hard-rock band Def Leppard (No. 10).

System of a Down’s total more than doubles the first-week figure of the band’s breakthrough album, “Toxicity,” which not only debuted at No. 1 in 2001 with sales of 222,000 but also showed staying power, reaching a total of 3.5 million in the U.S.

Will there be a seventh different No. 1 next week? The biggest challenger figures to be Audioslave’s “Out of Exile,” which came out Tuesday.