A few thoughts on the baby names series:
The Social Security database is not perfect - what is? The site admits it omits people who never applied for a SS card - which includes people who worked before SS became effective, people who died before applying a SS card, and illegal immigrants. The illegal immigrant item is interesting - people will sometimes use a phony SS number to get work, pay SS taxes, and then not be eligible for SS benefits; but if they never applied for a SS card, they are not in the SS name database.
Some interesting insights on baby names are found in Levitt and Dubner's "Freakonomics", chapter 6.
I found many series are U shaped. I also found a few series with a name temporarily made more popular by a famous person (Franklin for FDR, Marilyn for Marilyn Monroe, Shirley for Shirley Temple), but these names were popular before those people became famous too.
The percentage of the Hispanic population to total US population is increasing, and consequently Hispanic names are being more popular. I believe this affects the popularity of non-Hispanic names.
[NEAS: Good points]
Thanks,
Joe Orez