Our Avocado tree produces hundreds, maybe thousands of fruit, but all but a half dozen or less actually grow up and survive as regular sized fruit. The fruit starts falling off when they become golfball-ish size. The tree seems healthy. I live in Cape Coral, Florida (SW).
Certified GKH Gardening Expert
It is very normal for them to drop many fruits, as they will not make it to maturity anyways. This is a survival adaptation so that they get, at least, a few fruit.
It is likely that the soil lacks a sufficient amount of phosphorous and potassium to sustain a large fruit crop. I would make sure to fertilize the tree with a specific avocado fertilizer yearly, or add a good layer of compost around the area each year. This will help maximize the fruit production, as well as keep your tree healthy throughout the year. This article will help: https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-tree-growing.htm