USC's quota should be around 125 this year. With 11 chapters, and a new one chartering after bid day. Sooooo yeah. Some will drop during the new member period and they will probably initiate about 110-115 or so.
They have to add more sororities to keep up with the number of girl rushing or pledge classes would be astronomical. When I rushed there were 9 houses, and two new ones joined (Phi Mu and Alpha Gamma Delta) during my four years. They have a schedule new chapters that will charter every other year starting this fall. I think it's Pi Beta Phi this fall, Alpha Xi Delta in 2016, then potentially AOPi in 2018. It's definitely needed. South Carolina has way less houses and the same amount of girls rushing as other SEC schools, so they are trying to even that out.
I know my chapter officially has two Recruitment Chairs and two New Member Educators (basically new member moms) this year to keep up with the volume.