Have you tried Google Analytics?

Google Analytics is a free tool provided by Google which will analyze your web site usage. It will monitor your site and will generate reports such as
* number of users visited
* number of minutes spent on the site
* peak times
* place where users came
* what explorer used, etc.
This list is simply a short list of features. See for your self by visiting,

https://www.google.com/analytics/home.

You can log in using your GMail Id and password. Then you have to add your site to analytics and it will give you a script file which you needs to put in to your site. That's all to worry then Google will do the reporting to you.
Happy analysis.