Complex sentence: The magazine had a circulation of 621,068 copies in 2007,461,694 copies in 2009,448,303 copies in 2010 and 431,989 copies in 2011.
Split into simpler sentences: The magazine had a circulation of 621,068 copies in 2007. The circulation of the magazine was 461,694 copies in 2009,448,303 copies in 2010 and 431,989 copies in 2011.