The following two books provide descriptions of hand-to-hand/CQB in Iraq. They won't provide stats on frequency but are certainly detailed.

Of the two I found House to House far more compelling and it includes a detailed description of literal hand-to-hand combat in Iraq (not only CQB w/firearms but a harrowing knife fight).

My Men Are My Heroes
http://www.amazon.com/My-Men-Are-Her.../dp/0696232367

House to House
http://www.amazon.com/House-David-Be.../dp/1416574719