Billboard: Pink Floyd, 'The Dark Side of the Moon' At 40

Billboard reports:

Despite only reaching the No. 1 spot for one solitary week, the album continues to hold the record for the most weeks charted on the Billboard 200 (over 800 weeks!) and was a constant feature on the Billboard 200 from its initial release until 1988 – returning to the chart in late 2009 after Billboard revised its chart eligibility rules regarding older releases. It is estimated to have sold over 45 million copies worldwide, while its artistic legacy is arguably even greater.