That really depends on the breed of of chickens you have. 50-70 grams is a average across the board for chickens. My Brahmas and Orpington tend to lay larger eggs and I have had a few in the 90gram range from them. The double yolkers from my others were usually around 90grams as well.
Depends on breed. Jumbo eggs are 70g and over, so 90g is really big.
My Bielefelders average 52-58g; my Lemon Cuckoo Niederrhiener ave 60-70g with the largest being 78g double yoker. All birds are not yet a year old.