The Big Bang Theory started off slowly in the ratings, failing to make the top 50 in its first season (ranking 68th), and ranking 40th in its second season. When the third season premiered on September 21, 2009, however, The Big Bang Theory ranked as CBS's highest-rated show of that evening in the adults 18–49 demographic (4.6/10) along with a then-series-high 12.83 million viewers. After the first three seasons aired at different times on Monday nights, CBS moved the show to Thursdays at 8:00 ET for the 2010–2011 schedule, to be in direct competition with NBC 's Comedy Block and Fox 's American Idol (then the longest reigning leading primetime show on U.S. television from 2004 to 2011). During its fourth season, it became television's highest rated comedy, just barely beating out Two and a Half Men (which held the position for the past 8 years). However, in the age 18–49 demographic (the show's target age range), it was the second highest-rated comedy, behind ABC 's Modern Family. The fifth season opened with viewing figures of over 14 million.