Looks like it's 1% between 1550-1600. I couldn't find stats for an actual perfect score. Saying it's crowded I guess is ok, but is a matter of perspective. Like the top 1% of income earners saying their yacht club is crowded. Maybe true, but only for a very small number of people who could choose to go somewhere else if they actually wanted to.

http://go.collegewise.com/how-many-people-get-a-perfect-sat-...