Ever since December 2012, WordPress stats count not only the numbers of visits to blogs, but numbers of visitors as well.
Numbers of visitors are always lower than numbers of visits, as many visitors see more than one blog post or page.
So far, the record month for the number of visitors to Dear Kitty. Some blog was January 2013, with 11,221 visitors.
In April 2013, the month which is just finished, that record was broken: 11,904 visitors.