the EPL. A partial re-post of one of my recent posts might be appropriate here:

Over the last 20 years, Spanish clubs have made 29 appearances in Champions League semifinals (incl. 12 RM and 10 Barça), and have won it half the time (6 RM, 4 Barcelona). An additional 4 times, Spanish clubs (Valencia & Atletico Madrid) were the losing finalists, to other Spanish clubs in most cases.

No other European league came close to this performance. Spain produced 9 more UCL semifinalists than the EPL (20) over the same period; in both cases, 6 different clubs were semifinalists, but a few clubs dominated (ManU, Liverpool, and Chelsea for the EPL). English clubs won the Champions League 4 times; less than half as often as Spanish clubs.

If you extend history further back, the story is similar. La Liga teams have won 17 times since the tournament's inception (1956), compared to 12 for the runners-up (England and Italy). Spain has also produced 28 finalists (tied with Italy), compared with 19 for England. And Spain has had the greatest number clubs who have made it to the Champions League since the current format was adopted, at 13 (England has had 10).

https://en.wikipedia.org/wiki/European_Cup_and_UEFA_Champions_League_records_and_statistics

https://www.cougarboard.com/board/message.html?id=19506853

Looking at the Europa League might also be helpful here. Spanish clubs have won 8 of the last 20 tournaments (Sevilla, Atleti, Valencia), compared to 3 for EPL clubs. A count of finalists and semifinalists would show even more Spanish dominance, as there have been a number of years in which 2 or even 3 of the semifinalists were from La Liga (but I'm too lazy to go back and verify the stats on this one).

https://en.wikipedia.org/wiki/UEFA_Europa_League