Cloudy Tank Glass

I have had my 55 gallon tank set up for 4 years now. Over the last year the glass on the front and back have begun to get cloudy. The sides of the tank are still clear as the day I bought it. I have tried different scrub pads and a razor blade and nothing will take it off. What is odd about it is the cloudiness is in perfect horizontal stripes across the tank. Does anyone know what this is and how I get rid of it?? I attached a photo, its kind of hard to see... Please help!

I use white vinegar and scrub the glass with a brush and scrape it with a razor. That is if you have time to take your tank apart.