So that's around:
46% for Liverpool at Anfield, based off their being
28k ST holders(27k + 1k added with the increased capacity),
67% for Arsenal at the Emirates. based off there apparently being
40k ST holders in 2023.
67% for United at Old Trafford, based off there being
50k ST holders in 2023.
69% for Cheslea at Stamford Bridge, based off there being
28k ST holders in 2023.
Spurs are a weird one, 40% would put them lowest but I can't find any figures to support that. In fact, Simon Jordan seems to think there are 50k season ticket holders. That would put their season cards at around 80% of capacity, which would be the highest but I suspect he's wrong.
The only figure I could find for
City was 40k from 2017, assuming that's not changed since then(Arsenal's have lowered theirs by 5k)...
That would put City's ST holders seats at around 75% of the current capacity. Alternatively, that's around 65% of the new capacity.
Liverpool and possibly Spurs appear to have the least in the big 6 by a distance. I think City's is probably highest but the difference to Liverpool isn't the norm. Maybe that's a sign of where things are heading though.