I have statistics from WoW raid participation splitted in LFR and premade raid groups. LFR is the matchmaking version which adressed around 70-80% of all players and where Normal raids, the first premade difficulty, adressed around 20-30% of all players.
I also have a very current statistic of mythic dungeons players, which shows that around 1,5 million players played mythic dungeons at shadowlands launch, when the game sold for around 10 million copies, which is 15% of all players. Which is not really much.
And last but not least i have steam statistics, which show how many players completed New World dungeons.