taxable amount of annuity insurance payment

Hi, I have been paying taxes on the dividends and interest of an annuity insurance policy for the last 30+ years. That policy has matured and now I'm receiving payments. How much of the payment is taxable?

 

The premium was post tax payment, and every year the company sent the IRS and myself the amount of dividend and interest the policy accrued. I paid taxes every year on those dividends and interest.