There's always been a shortage. Up until the 1950's, polygamy was the law of the land. Wealthy men had as many as they could support, and single men sought the comfort of professionals. It did not help Chinese men that marriage has always involved the payment of a hefty bride price to the bride's parents. The ban instituted on polygamy, and the increasing tendency for women to stay single well into their late 20's (vs the traditional arranged marriage in their late teens) has actually increased the prospects for single men to at least kick the tires, rather than seek the services of professionals at the karaoke bar, massage parlor or hair salon.
Then why are there so damn many Chinese?.................