That graphic is the number of applicants selected for pilot from the board.
Go to this link on the portal to get the full slide deck. It will give you that same info for RPA, ABM, and CSO all from the same boards. They only publish numbers selected, never the number that applied. They make the same generic post on their portal page though saying the numbers are around 200 total applicants. If you add each total up, and assume 200, you've got over a 50% shot at getting picked up for something.