auto insurance companies

Why car insurance companies ask the previous pages statements?
My statements above pages shows the amount of premiums it was paying. I'm afraid my my new insurance company use that information to making up the price on my next renewal. Can you delete that information on the copy I send?
Of course they can block premiums. They just want: a) Make sure you had insurance before, B) See what your coverage before going to make a comparison. Do not worry about them "jacking up" right rates. Insurance is regulated by the state, no exchange or price flexibility here. Only hedging premium, after all that personal information is put in. Also, if you want that its companies do not want to give the best price you can?
State Auto Insurance Companies Home Insurance TV Commercial