Here's an interesting site which tracks the popularity of names over the last 120 years. As expected, Christian names have dropped in popularity over the last several decades. Although you can also see that "normal" names have also become less frequent too.
The Baby Name Wizard's Name Voyager
It is a neat tool though. You can just type in any name and it will give you the graph for any name beginning with what you typed, and if you hit enter again, you'll get it for just the name you typed.
Ha. My name has become more popular over the years, as shown below.
Another thing I noticed is that all the names seem to start dropping after the 1960's. The graph is based on number of children with that name in a year. I think part of that is not only names becoming less popular, but also the drop in birthrates after the pill and legalized abortion.
I still don't understand what is up with the bizzarre spellings of names nowadays. Even if it a normal name people are changing the letters so it will be "unique" e.g. instead of "Christine" it will be "Krysteen." Of course what is worse is some of the truly unique names people come up with, e.g. "Dweezel" or "Moon Unit." Nouns are probably best avoided also in my opinion.