This depends on five main factors... (1) age (2) breed (3) nutrition (4) health and (5) where you live.
Age: Chickens start laying at about 18-24 weeks of age and will be fully productive for 2-3 years.
Breed: The most highly productive breeds (like a Leghorn) can lay up to 300 eggs per year, most common backyard chicken breeds are in the 200 to 240 range. Some specialty breeds will lay fewer.
Nutrition: "Layer Feed" either pelleted or crumbled has the optimum balance of nutrition for layers and optimizes the number of eggs laid. Hens that do not receive adequate high quality feed will divert nutrition to life support, and egg production will be reduced.
Location: Chickens molt (shed or take on more feathers) twice each year and during that time, energy is diverted to the molting process not egg production. In colder climates, hens take longer to molt which cuts into egg production. In mild climates, chickens might molt in 2-4 weeks each cycle and in colder climates as much as 4-6 weeks.