I'm at 50% for the year; 32/64 commutes. I'm just behind last year's 40/64 as of April 1 and I'm about 100 miles off last year's mileage total to date. I told my son just the other day that someday he'll be able to track the climate change through my bike mileage journal.
I don't have studded tires and I'm not in a bike friendly area. I rode when I could and that often meant riding in 0 degrees because the roads were dry. Whenever it warmed up (20 degrees was warm) it seemed to snow.
The only real change (aside from layers) that I made for the winter was to use platform pedals and wear boots. I could have benefited from the platforms yesterday when the ride home was through a very heavy snow (my snow crusted helmet from yesterday).

I'm totally over the winter crap and I really do need to stop talking about it and just get studded tires on one of the spare bikes!