Elite tennis is becoming an old person’s game, in both the men’s and women’s circuits.

The average age of the players ranked in the top 10 has been rising steadily over the past 10 years, according to an analysis of Association of Tennis Professionals (ATP) and Women’s Tennis Association (WTA) rankings data made available on Jeff Sackmann’s Match Charting Project Website.

In 2008, the average age of all male players who made it to the top 10 of the ATP rankings sometime during the year was 24.4 years (we take into account any player who has been ranked in the top 10 at some point during the year). Since then, it has risen steadily to reach 28.9 years in 2015.

Data for the current year has not been used for this analysis.

Similarly, the average age of players ranked in the top 10 of the WTA rankings has increased steadily from 23.6 years in 2008 to 27 years in 2015.

The men who made it to the top 10 sometime in 2015 include Roger Federer, who first entered the top 10 in 2002; Rafael Nadal, who first got a top 10 ranking in 2005; and Tomas Berdych and David Ferrer, who reached the top 10 in 2006.

Among all the male players who were ranked in the top 10 in 2015, only Kevin Anderson reached the top 10 for the first time that year.

The women’s circuit is a bit different, though it has its share of veterans as well. The top 10 WTA rankings for 2015 included Venus and Serena Williams, who made it to the top 10 for the first time in 1998 and 1999, respectively, and Maria Sharapova, who broke into the top 10 in 2004. However, six women (Carla Suarez Navarro, Ekaterina Makarova, Garbine Muguruza, Karoline Pliskova, Lucie Safarova and Timea Bacsinszky) entered the top 10 in 2015.

If we were to look at the top 10 ranked tennis players in terms of “vintage in the top 10" (number of years since they first made it to the top 10), we can see that the average vintage of the top-ranked men’s players has been increasing steadily over the years.

For example, the average top 10 ranked men’s player in 2015 had reached the top 10 at least six years earlier. On the other hand, the top 10 ranked male players in 2008 had been in the top 10 for an average of two years.

The average vintage of women in the top 10, on the other hand, has remained broadly constant over the years.

So, what explains the steady increase in the average age of the top 10 ranked women’s players? Are they maturing, and thus breaking into the top 10, at a later age?

The average age of female debutants in the top 10 (players who have been ranked in the top 10 for the first time in their careers) has also increased over the years.

The year 1990 was an unusual one in the women’s tour, when 14-year-old Jennifer Capriati made it to the top 10. Even excluding that, it is clear that women’s players have been breaking into the top 10 at higher ages.

In fact, we can see a steady rise in the men’s graph as well, suggesting that vintage is not the only factor that explains men’s top-ranked players becoming older by the year.

Based on this data, it is unclear why tennis players are breaking into the top 10 at an older age. But the fact that top-ranked players are getting steadily older cannot be disputed.