Does anyone know of a way to automaticaly log time spent on each individual part assembly or drawing within SolidWorks?

I need to know how much actual time was spent on modeling a Part. When starting a new part a timer must start counting the time untill the part is not the active window anymore then the counter must pause intill it becomes tha active window again. Similar for Assemblies and Drawings.

I often find that quoting for jobs is nothing more than a "thumb suck" knowing the actual time that was spent on a project can help a lot when quoting for the next job, and doing this manualy is a problem as yo have to remeber to start and stop the timer.