Hi Ade,
Fruit every other year is a misconception ;-? My olives fruit every year, albeit one year is "stronger" than the other.
Yield is related to many factors, including age, trimming, water, soil conditions etc.
For the record, I have ~ 25 trees on 4000 sq. meters.
I get annually between 180 - 230 kilos of oil, but then again I don't water or fertilise or any of that stuff, just real natural bio oil.
gotta run, I'll pick up on this tomorrow,
nick