None for a couple of years, but 2 so far this year.
One on the road bike - a tiny, sharp pebble poked through the front tire. That tire is getting old and I have been thinking of replacing it, so now I really have to do it.
The other was on my MTB bike during my trip up to Maine. That one was a bit annoying, seeing that the bike is about a month old. the rim tape is not tape, but a molded rubber. The spot where the two ends of the tape are joined was kind of rough, and after a couple of rides, the rough spot wore through the tube. At first I could not figure out why the puncture was on the inside of the tube, but then when I lined the tube up with the rim and the hole lined up perfectly with the rough rim tape joint, that was it. I put a piece of electrical tape over the rough spot.