The average age of the top 100 have increased from about 25.25 years in the mid 90s to a record (since August 1994) 26.88 years last month (click here for full article and graph
The increasing nature of this statistic is mainly due to there being less young players (under 21) at the top. Until last year, there was at least one teenager in every year end top 100 since ATP rankings began in 1973. The 2009 year end ranking had not a single teenager, furthermore, not a single 20 year old.
Please discuss why you think the average age of the top 100 is increasing. Is it simply a deviation from the mean or perhaps a weaker younger generation? Another reason could be that the courts are, in general, slower than before and hence more endurance (which usually comes with age) is needed to win matches
My three part article
on age and ranking also looks at the average age players achieve their career high and the youngest players to crack the top 5, 10 and 100. I also discuss the average age top players reach certain ranking milestones. For example, on average, number ones (since Edberg) entered the top 500 before turning 17 (16.86) and reach the top 100 before adulthood (17.94).