Mary and John were the most popular baby names in the U.S. for decades. Eventually, they were replaced with names like Robert, James and Lisa. Then Robert, James and Lisa were overthrown by names like Jessica, Jacob and Emily.

But you already know that the most popular baby names have evolved over the years. That's just common sense. :)

What you may not know, however, is that being a popular name isn't what it used to be!

Today's top names are not as dominantly popular as the most popular names of yesteryear.

The following list displays the #1 baby boy and baby girl names by decade. The percentages represent the proportion of babies given these name during each 10-year block.

1880s	John, 7.6%	Mary, 6.5%
1890s	John, 6.6%	Mary, 5.6%
1900s	John, 5.8%	Mary, 5.2%
1910s	John, 5.4%	Mary, 5.6%
1920s	Robert, 5.1%	Mary, 5.7%
1930s	Robert, 5.4%	Mary, 5.2%
1940s	James, 5.3%	Mary, 4.3%
1950s	James, 4.1%	Mary, 3.2%
1960s	Michael, 4.2%	Lisa, 2.6%
1970s	Michael, 4.1%	Jennifer, 3.5%
1980s	Michael, 3.5%	Jessica, 2.5%
1990s	Michael, 2.3%	Jessica, 1.5%
2000s	Jacob, 1.3%	Emily, 1.1%

The early #1 names saw widespread usage. As the years elapsed, the usage of these top names waned.

And it isn't just the #1 names being used less frequently. For instance, compare the top ten names of 1910 to those of 2010.

Top Ten Names of 1910:

1. John (5.5%), Mary (5.4%)
2. James (4.4%), Helen (2.5%)
3. William (4.2%), Margaret (2.0%)
4. Robert (2.7%), Dorothy (1.7%)
5. George (2.6%), Ruth (1.7%)
6. Joseph (2.5%), Anna (1.5%)
7. Charles (2.3%), Elizabeth (1.4%)
8. Frank (1.8%), Mildred (1.4%)
9. Edward (1.6%), Marie (1.1%)
10. Henry (1.4%), Alice (1.1%)

Top Ten Names of 2010:

1. Jacob (1.1%), Isabella(1.2%)
2. Ethan(0.9%), Sophia (1.1%)
3. Michael(0.8%), Emma (0.9%)
4. Jadyen (0.8%), Olivia (0.9%)
5. William (0.8%), Ava (0.8%)
6. Alexander (0.8%), Emily (0.7%)
7. Noah (0.8%), Abigail (0.7%)
8. Daniel (0.8%), Madison (0.7%)
Mli>Aiden (0.8%), Chloe (0.6%)
9. Anthony (0.8%), Mia (0.5%)

In 1910, about 29.0% of all baby boys were given a top ten name, versus about 8.4% a century later. For girls, the percentage decreases from 19.8% to 8.1%.

So what does all of this mean? Well, as the reigning baby names become relatively less prevalent on birth certificates, the race for #1 will become tighter (because many more names will have a real shot at reaching the top spot). Also, the top ten lists (like those above) will become more volatile and less predictable from year to year.

It also means that you should think twice before shunning a "popular" name simply because it's popular. Because, once you start looking at the numbers, it's easy to see that popular names aren't quite as popular as everyone assumes. :)