How rare are gigantamax raids ?

I am rlly wondering because i defeated raihan like 3/4 days ago and i already caught 9 gigantamax pokémons, even the 1st 5stars raid that i tried was a gigantamax corviknight (that i didn't manage to catch, but that brings the number to 10 already) and then my brother used 2 gigantamax curry (or whatever these are called) and idk how many wishing pieces (he has been playing for longer than me, idk how long exactly) and all he got was just a single gigantamax orbeetle, so i don't understand at all if those are supposed to be rare or not :/