GitHub has this info available via their builtin dashboards, e.g., https://github.com/cncf/devstats/graphs/traffic
I don't know what the API looks like to pull this but since we have data for stars and forks, maybe we add that to the dashboard: https://kubevirt.devstats.cncf.io/d/3/stars-and-forks-by-repository?orgId=1
Maybe we call it 'stars-forks-and-clones' ;)? or a separate one for just clones