This table describes how many people visit Yosemite each month, so you can get a sense for which months are busier than others. (Data are from 1985-2007.)
If you're looking for more in-depth statistics for Yosemite, you can get them from the Public Use Statistics Office.
Did You Know?
In March 1987, the largest historical rockfall in Yosemite National Park deposited an estimated 1.5 million tons of debris at the base of Three Brothers, closing Northside Drive for several months.