Welcome to BYC!
Do you know what breed your chickens are? If not, you can post some photos of them here and we can likely get them ID'd for you. Knowing what they are is going to factor into the expected egg production rate for each bird.
You mentioned you've had them 1 and 2 years, were they chicks when you got them or were they already grown birds? Like breed, age will effect the expected egg production as the first two laying cycles of a bird's life are their most prolific (the first is from the time they strart laying around 6 months of age until the first molt around 18 months and the second is when they resume laying after that molt (often not until the following spring) to the second molt (the following fall).
When they aren't able to be loose in the large yard, do you have a run that they are confined in or are you confining them inside the actual coop structure at those times? If the latter, how many hours per day, on average, are they confined like that? What are the dimensions, in feet, of the coop and, if you have one, run?
What feed are you giving them? Diet is another factor that can significantly impact the production of a given bird.