How large a percentage of the men infected with chlamydia do not realise they carry the infection?

Explanation

Chlamydia infection is the most common sexually transmitted infection (STI), especially amongst young people. It is caused by the bacterium Chlamydia trachomatis and can be effectively cured with antibiotics in less than a month. You can be infected for years without knowing so, but can still pass on the infection. Around half of all men experience no symptoms, which otherwise include painful urination or a swollen penis. In women, an infection can lead to pelvic inflammatory disease which in turn can cause sterility.