The number behind these charts comes from the Social Security Administration, which maintains a database of baby names going back to the late 1800s. For a sense of how unusual the Clinton effect on the name "Hillary" has been, look at the charts below. They plot the trajectories of the names of all presidents and first ladies since the Reagans, for the years starting in 1970.
The y axes aren't the same scale on all of these charts, because some names (like William) are orders of magnitude more popular than others (like Barack). The idea is to compare the relative trajectories of each name over time, particularly as they relate to the time each couple resided in the White House.
What stands out, first of all, is that nearly all of the names trend downward. This makes a certain amount of sense when you consider that the typical president or first lady is going to have a name that was popular 40 or 50 years ago. A name that was popular in 1970 is probably not going to be popular today.
You'll also notice that in most cases, a first couple's time in office doesn't seem to have much bearing on the overall trajectory of their names' popularity. The two huge exceptions to this are Hillary, as discussed above, and perhaps unsurprisingly, Barack. "George" may have gotten a small bump during George H. W. Bush's brief tenure, but the effect wasn't durable.
Part of the Hillary effect is probably due to Hillary being a less common name than some of the other ones overall. For instance, in 1992 there were about 2,500 babies named Hillary, 8,300 named Laura, and 11,500 named Michelle, according to the Social Security Administration. With a less-common name, it's more likely that a single famous person can alter the trajectory of that name.
It's also interesting to compare the changes that took place only during the years that the first couples were in the White House. The chart above plots the change in each name over the 4 or 8 years starting with each president's respective election year. I had to omit "Barack" from these charts, because the name is such an extreme outlier: there were 5 babies named Barack in 2007 and 52 in 2008, an increase of 1,000 percent.
Again, Hillary's exceptionalism is on display here. The popularity of that name fell 90 percent from 1992 to 1999. By contrast, the frequency of "William" fell by just about 10 percent over the same period.
It also looks like the popularity of first ladies' names falls more sharply than the popularity of presidents' names during their time in office. But again, it's not clear just from these charts if that's a true presidential spouse effect, or just a reflection of the natural long-term trajectory of those names.
One final thing to note from the topmost chart: "Hillary" enjoyed a brief resurgence in 2008 during her primary fight with Barack Obama. We may expect to see a similar Hillary effect in 2016 — particularly if she goes on to win the White House.
A reader suggested I look at the trend for "Monica." Here it is:
You can see the sharp drop after 1997 -- the Lewinsky scandal became national news in 1998. Proving that baby names can be affected not only by the people who occupy the White House, but what they do while they're there.