I hear that it is rare to contract chlamydia or gonareaha via oral sex from a female. how rare in percentage are the chances?

Oral Sex and STDs: It is common. Not rare. Humans who perform oral sex on the penis are at risk of contracting gonorrhea and chlamydia. They often do not know that they have this infection because it is often symptom free in the throat. The male who has received the oral sex, however, if he gets infected, is most likely to get symptoms in his penis within four to five days post exposure.