general tendency of sticking by "feeling," impression, and anecdote rather than actual statistics.
It just hasn't been falling that steadily at all, 22-28 over a period of five years is really not that dramatic of a change or even a pattern, and even then its peak of popularity would have been 2001, not the eighties. It's still more popular now than it has been in any year of the 80s. A lot about names is subjective, like... whether they're nice or not... is subjective, and you might have gotten the impression that
Anna is "dated to the eighties" because of the purely subjective sample of
Annas that you happen to know, but there are a few objectively measurable things, like popularity over the years. Even with regional variations...