What is the likelihood that std occurs the only time you have unprotected sex?

Unprotected Sex.....: I think this question is valuable for many people. But, there is no likelihood to give you statistics and hard facts. One should consider that every sexual encounter can put them at risk for disease. This leads to healthier choices to use condoms and to get into relationship with partners you can learn to trust. But, any unprotected sexual encounter can lead to infection with an std.