I only count b/c I was anal enough to start filling in a spreadsheet I found online for keeping track of rides and miles during the year. Since I started commuting in the spring, I thought it would be fun to keep track of. It has been. It's kinda cool to see how quickly the miles can add up. And a number that sounds foreign and amazing to friends and family (close to 2000 miles ridden since March) is actually easy to achieve if you commute.
I've had a couple long vacations and some wheel issues (which with only one bike means no commute), but between mid-April and now, I've gotten in 113 round-trip commuting days (23 days vacation/holiday; 28 missed for lack of a functioning, intact rear wheel) for almost 1600 miles total commuting. Guess I make platinum on mileage if nothing else...
Next year I'm gunning for 200 round trip days, which would have me around 3500 commuting miles (commute's close to 15 miles RT).