Strike on Egg Laying

[lost chicken]

I am having the same problem , I have 2 yr old chickens and 1 yr old chickens and last year I was getting alot of eggs and this year I think I have only gotten about 18 eggs a day and I have 30 chicke s what do I do, everything is the same food house and watef and nite time light, I even went and bought 17 more chickens they are 8 months old , help me with a suggestion please John chi ken coop! Thank you, lost chicken