As has been mentioned, it's hard to generalise and your local agricultural extension people are the best people to talk to about specifics in your particular area.
If everything is perfect, you can get 1-2lb of dried hops from a full-grown plant, but that does assume everything is right, and does depend on variety (sexy aroma hops tend to have lower yields than "boring" bittering hops). It generally takes three years for them to get up to full speed - it's not quite as simple as 1/3 of the adult crop in year 1, and 2/3 of the adult crop in year 2, probably more like 10-20% in the first year.
The thing to remember is that hops are from temperate zones - the classic hop areas like Bohemia and Kent are 49-52°N. I'd imagine in Kansas you're getting pretty close to the 35°N limiting latitude for growing them successfully. It's not just a matter of climate - although they need a good frost to "reset" them in winter, they are also very sensitive to day length and that's what prevents them cropping successfully nearer the equator.
36" of rain is if anything on the high side - 24-30" is typical of the traditional hop regions - so fungal diseases may be a problem. OTOH the rain does have to come at the right time - August is the wettest month of the year in parts of Kent.
They're hungry plants that appreciate deep rich soil and being kept well-fed.