There is no definitive answer to this question as it depends on a number of factors, including the definition of riding a unicycle and the population being considered. However, some estimates suggest that around 1% of the general population can ride a unicycle, although this number is likely higher for people who have had some prior experience with cycling or similar activities. For children, the percentage is likely to be even higher, as they are generally more adept at learning new physical skills.
So, while we can't say for sure what percentage of the population can ride a unicycle, it is safe to say that it is a relatively small minority. If you're one of the few people who can ride a unicycle, congratulations - you're part of a select group!