Where can I find park attendance numbers for Disneyland? What is it like on Mother's Day? When is it busiest?

I'm a frequent Disneyland attendee and am looking for some infomation outside of the usual "It's busiest on the weekends, holidays, Christmas" etc. What are the actual numbers and how can I find them? I would like to go this Sunday on Mother's Day and need the average attendance number for previous years.