Based on what I'm seeing from last year, 271 teams had signed 1+ transfers in 2022-2023. Of the team's who signed at least one transfer, the average amount of players they signed was 4.9.
I haven't found a solid data source of how many LEAVE for these types of schools, but the inverse can be helpful as well. I'd imagine those numbers will be higher this season.
I also read somewhere that 33% of NCAA basketball players end up transferring at some point in their careers. That stat isn't overly helpful as there could be repeat offenders, but also helpful context.
This isn't Uncle Naismith's basketball anymore...