Back in 1906, only 2 of the 2,000 most popular baby names in the U.S. began with the letter Y. One hundred years later, in 2006, that number had jumped to 17 -- an increase of 850%.

Though it's hard to know exactly why this upswing occurred (outside of a growing general interest in unique names), it's not too hard to see when it happened.

Before the the 1970s, only three Y-names -- Yolanda, Yvette and Yvonne -- were able to maintain any sort of lasting appeal in the eyes of American parents. The few other Y-names that managed to become popular before 1970 (such as Yancy, Yee, Yetta, Yoshio, Yoshiko and Young) never became very popular, and they weren't able to stay ranked for more than a few years. (Actually... Yetta did rank higher and longer than the other names, but it too had fallen off the list after several decades.)

Then, during the 1970s, a new trio of Y-names -- Yesenia, Yadira and Yasmin -- became popular. (They debuted on the top 1,000 list for girls in 1971, 1975 and 1977, respectively.) More importantly, they were able to stay popular. In fact, all three still rank as of last year, and they've also inspired a few popular spelling variations (Yessenia, Yasmine and Yazmin).

After the 1970s, new Y-names began showing up on the "most popular" lists more frequently. They didn't fare as well as Yesenia, Yadira and Yasmin -- in fact, many of them (like Yaakov, Yamilex, Yulissa and Yehuda) only managed to remain ranked for one or two years total. But for every Y-name that fell off the list, there seemed to be a new one to replace it. Therefore, statistically speaking, Y-names had become more popular overall -- even if individual Y-names weren't able to remain fashionable for long.

Perhaps the most interesting thing about this new generation of Y-names is that, as their popularity has risen, the popularity of original Y-names has tapered off. In fact, Yolanda and Yvonne have now fallen out of the top 1,000 entirely, and Yvette will soon follow. This is likely because the old favorites sound stale next to such modern-sounding names as "Yareli" or "Yuridia."