Anyone who has taken a good look at the SSA's name popularity list knows how in recent years the share of babies given one of the top-ranking names has decreased quite a bit. What is not obvious from those stats, but becomes apparent to anyone studying name trends over longer periods of time, is that drop is an extension to the long-term trend since medieval times (when over half of the population of each gender got one of a few names). In fact, as recently as the mid-19th century, the most popular name for each gender (typically John and Mary) was given to more than 10% of babies. Since then, a variety of new name practices became more common (using surnames as first names, virtue names, nature names, alternate spellings, etc.) resulted in the "core classics" gradually becoming less and less used as a whole (while some name enthusiasts may not like those trends, such practices do result in fewer "burned out" names).
In the SSA-list era, this long-term trend has largely continued, although there was a slight regression during part of the first half of the 20th century. Even so, we went from 6-8% of babies in the 1880s given the top name (with the runners-up not far behind) to just over 5% during the early baby-boom era (when the top names shifted to Robert and Linda, which more frequent changes to the names themselves at the top of the list is the subject of a future blog post). By the 1970s we were down to 3-4% when Michael and Jennifer ruled the roost. However, that drop pales into comparison to what started happening around 1990 or so (I don't know if they had any influence or if it is just coincidence, but that was right after Beyond Jennifer and Jason, the first name book written by Pamela Redmond Satran and Linda Rosenkrantz, came out). Over the last 20 years or so the number of babies given a top name has dropped dramatically, to the point that the current top names (Jacob and Sophia) are given to barely more than 1% of babies (that's less than a third from the generation before, about a fifth from the generation before that, and less than a tenth from 150-200 years ago). That's why in the name community, we often say that unusual names are less likely to cause teasing and/or social outcasting than when you or your parents were growing up; on the other hand, those who like one of the top-ranking names but worry about popularity can rest knowing that those names are less common than what the similar-ranking names were when you were a kid. In the most recent SSA lists, it looks like this massive drop has begun to level off though (making circa 1990-2010 the "name deflation" era).
In my next blog post I'll be talking about how this name individuality vs. conformity has varied by gender.