Even IF you never know what part of the song you're gonna get in the 1 minute 30 second ED at the end of each episode?
BTW, here's that count so far:
Beginning - 14x (1, 2, 3, 4, 6, 7, 9, 10, 11, 12, 13, 17, 18, 19)
Breakdown - 2x (14, 21)
Solo - 2x (15, 20) (also used as BGM in the training montage in 16, but that's not the ED)
Ending - 3x (5, 8, 16)
Edit: I had misclassified 13 as ending with the end of "Roundabout;" it was in fact the beginning!