"Dark Side Of The Moon" Hits 1500 weeks on the pop charts

Pink Floyd headphone classic "Dark Side of the Moon" has now spent some 1500 weeks on various Billboard charts. Billboard confuses the issue a bit -- I always understood that the album would STILL be on the Top 200 album charts but Billboard changed the rules and decided after a certain time new albums would automatically switch to the Catalog Albums chart. This article seems to say it dropped off on its own. The article also says the CD has sold some 40 million copies worldwide, which puts it in a race with The Eagle's "Greatest Hits" and Michael Jackson's "Thriller" for the bestselling album of all time. (Pink Floyd has sold about 15 million copies in the US, so it must have moved 25 million copies in the rest of the world.)