It varies depending on market conditions.  As of 06/11/2018 @ 2:55pm GMT-8 here is a ETH projection off a website that projects monthly income:

https://whattomine.com/coins/151-eth-ethash?utf8=%E2%9C%93&hr=28000.0&p=251000.0&fee=1&cost=0.1111&hcost=172700&commit=Calculate