It's interesting to note that the increase in the use of Justin has a matching (if slightly lagging) increase in literature[1], while the increase in Jacob isn't[2].
[1] https://books.google.com/ngrams/graph?content=Justin&year_st...
[2] https://books.google.com/ngrams/graph?content=Jacob&year_sta...
I just figured out that it shows a random one when you don't enter a query, that's cool.
Other spikes: Linda, Jordan, Mason, Deborah, Beth, Paige, Laurie, Chloe, Megan, Stella, Stacey, Kim
It seems like female names are much more likely to have sharp spikes in popularity verses male first names.
The other names show similar shapes:
Meg: http://rhiever.github.io/name-age-calculator/index.html?Gend...
Jo: http://rhiever.github.io/name-age-calculator/index.html?Gend...
Beth: http://rhiever.github.io/name-age-calculator/index.html?Gend...
The second bump for Meg could be due to Meg Ryan?
My wife dug in her heels pretty early in the pregnancy for a name that I later learned was a character on a TV show. Judging by the site, she's not the only one. The peak is still under a hundred, so not as embarrassing as, say, characters from 90210.
Names (just like everything else) have fads. Fads come and go.
It's easy to see why names such as "Buzz" have the curves that they have (space race), but it's hard to trace any event that influenced more common names. For example, check "Jacob", "Justin". Does anybody have an idea as to why these curves have this shape?