I doubt you're going to wrap your hands around any definitive data. For instance, myself, like others, often "come and go" as the mood strikes. I'd rather be running my K-27 in the yard in the Summer, but in the Winter I usually get back to virtual railroading.

Personally, I wouldn't worry too much about it, since about 37% of all statistics are just made up anyway. (I just made that up...)