Does this not depend on where and when in the world? What about short, poor, ugly people?
Women get the top spot because they have been globally discriminated against since the dawning of time.
Almost every religion that I know of has some sort of religious doctrine claiming that women are property and inferior to males.
Jews have been persecuted by various groups for thousands of years, murdered by the millions just because they are Jewish.
LGBT comes in third because no matter your gender, race or religious leanings, being gay will always stir up the wrath of fundamentalists that believe homosexuality is a sin and that's a universally held view unfortunately.
Being short and ugly never elicited the murder and persecution of a group on a global scale, sorry try again.