Ive been on when the ratio of RPs to other servers was about 3:2
Most of them have a brickcount of less than 1000 and just run a mod or say 'build and play' or something. Theyre all basically freebuilds that are themed to be a city or something, instead of being a real role play. My Zombie Land server will be more of an RP than most servers that claim to be.