That changes as you get older, turning about 50% of men over 60, and every 5 years goes down by another 10%.
The real problem is not the % of men deemed unattractive, but how it is defined. (I am using rough percentages, here)
80% of female attractiveness is how much they try. Weight, hair, makeup, clothing, mannerisms etc. 20% is not controllable by the woman. Bone structure, etc. Plastic Surgery works pretty well for women. End result, the pretty women are those that want it bad enough and does the hard work (about an hour a day) to make themselves pretty. Yes, not all women can do this, but most can.
But male attractiveness is the other way around: 20% based on how hard you try and 80% not controllable by the men. Height, status, money are mostly determined by your parents. The wrong genetics and upbringing and you are average intelligence, short, OR do not like conflict (he has no confidence....). To be really attractive you need to be above average intelligence, above average height, and the right personality. Plastic surgery does little to make men more attractive to women.
This results: the pretty women are the ambitious ones while the handsome men were just lucky. As men get older, the nice attractive men get married and stay that way. By the time a man is 40, most of the attractive men are either not interested in settling down except with a bisexual supermodel that knows how to cook and is willing to share her girlfriend, or are total a-holes that no one can bare to spend time with.
Women (both attractive and not) date these attractive men and think all men are a-holes, all the while refusing to go out with the short OR poor OR low quality job. A short, poor janitor has no chance, no matter how wonderful a husband he would be.
There is a reason why taller men get married earlier, and taller women get married later.