Season 1
17 episodesAVG 8.07
Best: E17 "The Tangerine Factor" (8.5)
Season 2
23 episodesAVG 8.16
Best: E11 "The Bath Item Gift Hypothesis" (9.1)
Season 3
23 episodesAVG 8.20
Best: E22 "The Staircase Implementation" (9.0)
Season 4
24 episodesAVG 8.03
Best: E1 "The Robotic Manipulation" (8.7)
Season 5
24 episodesAVG 7.93
Best: E7 "The Good Guy Fluctuation" (8.5)
Season 7
24 episodesAVG 7.85
Best: E9 "The Thanksgiving Decoupling" (8.8)
Season 8
24 episodesAVG 7.47
Best: E15 "The Comic Book Store Regeneration" (8.1)
Season 9
24 episodesAVG 7.57
Best: E11 "The Opening Night Excitation" (9.0)
Season 10
24 episodesAVG 7.40
Best: E24 "The Long Distance Dissonance" (8.6)
Season 11
24 episodesAVG 7.33
Best: E24 "The Bow Tie Asymmetry" (9.0)
Season 12
24 episodesAVG 7.47
Best: E24 "Unraveling the Mystery: A Big Bang Farewell" (9.5)