While 99% of competitive smashers are between 11 and 23 years old (with most of the others being 24-27), I'll speak for anyone who has ever played smash:
If I had to guess, it would be a bell curve centered around 16 with a standard deviation of 3 years.
This would imply that there are as many 13 year olds as 19 year olds, and 68% of smashers fall into this range of 13-19 years old.
Similarly, there would be as many 10 year olds as 22 year olds, and that 95% of people who have played smash fall into this 10-22 year old range.
In reality, the bell curve would be marginally right-skewed (that is, there certainly aren't as many smashers who are 1 year old as are 31).
Another observation, is that, in general, every year smash has been out, the the curve flattens out slightly, spreading to the right as some people continue to play smash (but staying roughly the same on the left as new players are attracted), thus moving the mean a portion of a year older.
Also keep in mind that the age distribution for smashboards posters will be a tighter, slightly higher curve since the younger a smasher is from the mean, the less likely they are to be able or be interested in posting here.
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