If the Roosters, Souths, Canterbury and the Eels all play their home games at the big venues, there's 100% from them right there.
Manly, Penrith, Cronulla, Tigers and Dragons is where things get complicated. I've got a short breakdown of where games could be scheduled whilst trying to be fair to the suburban based clubs.
Dragons: 4 x games in Wollongong (which don't count as Sydney)
2 x games at Kogarah
6 x games at SFS = 75% big venue games
Wests Tigers: 2 x Campelltown
2 x Leichardt
8 x ANZ = 66% big venue games. I know their fans wouldn't agree with this, but realistically their fan base is far more centrally located to the big stadiums than the other clubs in question.
Penrith: 9 x games at Panther Stadium
3 x games at Parra Stadium. 25% big venue games. Panthers won't draw big crowds at Parra unless they're playing the other western Sydney clubs, which completely kills off any home ground advantage.
Sharks: 9 x games Shark Park
3 x games SFS. 25% big venue games.
Manly: 9 x games Brookvale
2 x game Gosford (don't count)
1x game SFS. 10% big venue games.
Myself, like everyone else only want to see us play at Brookvale. Our ground should be the Wrigley Field of NRL. It seems like that won't be the case unfortunately. We would draw good crowds at Gosford for games against Newcastle, Souths or the Tigers. One marquee game at the SFS (ANZAC day double header? Manly V Sharks & Roosters V Dragons) There's the four 'Eastern' clubs playing on the one day, should sell out. The rest at Brookie, where we belong.
Roosters 12/12
Souths 12/12
Canterbury 11/12 (1 game at Belmore)
Parramatta 12/12
Dragons 6/8
Tigers 8/12
Panthers 3/12
Sharks 3/12
Manly 1/10
So by my count that's 102 Sydney games total, with 68 being played at the big venues. 68/102 = two outta three ain't bad.