Sources:

• https://www.imdb.com/title/tt1327801/
• https://glee.fandom.com/wiki/Glee_Wiki
• https://en.wikipedia.org/wiki/Lists_of_songs_in_Glee_(TV_series)

Wikipedia was used to verify what was on the Glee Wiki. A song here is counted as something that was performed in both the episode and on the album. Album exclusive songs and episode only songs do not count.

Microsoft Excel was used in order to create this graph.