I knew what yesterday was, but I wasn't online yesterday at all. Down with a migraine, and then had chores around the house. By the time I finished, it was basically time for bed.
I was sitting at an office staff meeting on a December 7th a couple years ago, and when I mentioned Pearl Harbor, several of the people there said, "huh?". I guess they read about it in high school, but it was back far enough that it didn't matter.
Hell, there are people who don't even acknowledge 9-11-01, either, and that was very recent.
67 years has a way of dulling the edge on collective memory.