That would work, however I think you would be better off simply recording each request with a timestamp. That seems to be the lowest level of granularity you are looking at. Not only is that code simpler to write, it will also not have to change when you want to do daily averages, 5 min. averages etc.
If you want to do all of your analysis in code, you could think of setting up a publish subscribe pattern: http://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern.
Your publisher would record each request and a timestamp and send it out to the subscribers. Each subscriber would analyze the data in a different way. For example, you may have a 5 min avg. subscriber that is calculating the 5min avg. and another subscriber that is calculating the 1 second avg.