User Login History

Summary:

How to view more than just the last login for users in report form

Content (required):

I have been asked to provide the average number of users who log in a month. I know this data is stored for at least a year as I can view access history when looking up an individual. I can't figure out if it's available in report form. The only field I am finding is the last login. This will be grossly inadequate as we have considerable variations by month. For example, any data pulled from January will not include logins from people who logged in in February or March. Any ideas?