We know women earn 74 cents for every dollar men earn, but why? 

Start with the reality that 80 percent of U.S. workers do routine production or service work, like answering phones or selling clothes, and their paychecks have shrunk. The other 20 percent of workers use advanced technology or make decisions about money, like engineers or stockbrokers, and their pay has increased. Yes, most women are in the first category.