Different part of the world the population differs. US, EUROPE etc have more female population because there is no gender bias, but in Asian countries like India, Bangladesh Nepal Srilanka more importance is given to males rather then females. So you will find the population of Indian men as compared to women is 1000 : 913. In some states it is 1000:836, They do sonography and sex determination is done and the baby is aborted if it is found to be female. It is some thing worst on earth.
According to most census' they claim there are approx 50-50. But it always seemed to me girls outnumber boys 3-5 to 1. which would make more sense if you look at ratios in animals world wide. One male could mate w/ many females. 1 fem can only mate w/ 1 mate at a time. propagation of the species.humans are (as of 200yrs ago) the only species that tends to mate monogamously. some swans/geese mate for life.