There are no official statistics from Airbnb, but this percentage is probably not large. And the reason of it that it is not so easy to get the status of a SuperHost, you need to follow a number of requirements. Here are the main requirements:
Communication. You need to maintain at least a 90% response rate.
Experience. You have to accept and complete at least 10 trips or 3 reservations with a total duration of at least 100 nights.
Cancellation rate. It does not have to be more than 1% (1 cancellation per 100 bookings). But except for cases provided for by the Regulations on the application of good reasons.
Rating. An average rating has to be at least 4.8 over the last 365 days.