Since I spend 70% of June-August in Yosemite (I'm a teacher and am lucky to have those months off), I have seen at least 100 bears over the years in Yosemite. Last year I only saw 5, but some years I've seen a dozen or more. In 2006 on a hike to Ten Lakes, I saw three different bears on different parts of the trail. While doing Clouds Rest a few years ago, I saw three different bears.
Incidentally, I've never seen an aggressive bear in the wild in Yosemite. Not once. Every single bear I've seen there has been shy and timid. They almost always run when they see you or move away, even the mama's with cubs I've seen. It always makes me upset when inexperienced hikers say, "I'm gonna take a gun with me out there..." as if black bears are lying in wait to maul you or harm you in any way. If you respect the bear and don't attempt to feed it, handle it or encroach on its area, it will respect you (as long as food isn't involved).
I don't count in my lifetime tally the bears I've seen in parking lots around Curry Village or crossing the road. I only count the bears I've encountered hiking in the back country.