https://github.com/ornetstats/stats/blob/master/o/main_guard_operators.txt
I do not know how to interpret this table. How many guards are there at any given time?
The list includes all relays having - the guard flag _and_ a - guard probability > 0%* now, 2079 relays currently. 732 of them have no ContactInfo set (representing ~30.7% guard probability).
*(as reported by https://onionoo.torproject.org)