It is more than 40%! Anything ‘out west’ (Denver and westbound), every city has pretty much a redeye, especially the 1 a day flight cities with transcon service (PHX, PSP, ABQ, SMF, SJC, etc). The true daytime flying is going to be the short hop LGB stuff, and you’ll be flying 3-4/leg days, besides a few daytime departures from LAX/SFO and a few others, everything else will be flown in the middle of the night.

Before the CBA, more than 50% of the pairings had at least one leg touching the redeye period, and I doubt that has changed much.