Taking your 99% effectiveness of the pill, the probability of the failure of that is 1%, or 0.01. The probability of failure of the pull-out method (done correctly) is 4%, or 0.04. Combining the two, means the probability of simultaneous failure is 0.01*0.04 = 0.0004, or 0.04%, or 1 out of 2500 times.
This is in the form of retinal activity equivalents to account for the various sources of vitamin A. The best sources of preformed vitamin A are in liver and fish oils. This includes beef, calf, chicken liver and cod liver oil.
Fat-soluble vitamin A (the kind we need to stop tooth decay and other diseases) is found in liver from grassfed or wild land and sea animals, raw milk from grassfed cows, egg yolks from free-range chickens, sea foods, and fish livers. This vitamin A is preformed (retinol).