High Impact Athletes is a new organisation set up by professional tennis player Marcus Daniell, which aims to spread effective giving in professional sport. As of February 2021, their website lists 9 member athletes, as well as 29 athletes who are not member athletes as they have not made a pledge at 2% or higher.
This question asks:
How many athletes with HIA pledges will there be at the end of 2021?
To count as having taken the pledge, athletes must commit to donating at least 2% of their earnings to effective charities. Resolution will be according to data from HIA themselves, who have been involved in this question's development. A current list is available here, but at the time of question writing it is updated manually, so it is not guaranteed to remain perfectly up to date.
If HIA ceases to exist for any reason, this question will resolve as <20. Athletes are not legally bound to their pledges, and so may renege on them. Athletes who have made a pledge but later decided to stop following it shall not count for the purposes of resolution. If HIA decides to change their minimum recommendation to more than 2%, athletes will count if their pledge is at least the minimum commitment at the time they made it. If HIA decides to change their minimum recommendation to less than 2%, athletes pledging less than 2% shall not be counted for the purposes of this question.