The number of women who leave the workplace to care for their children is on the rise, as the cost of child care grows exponentially. As this article on the Slate blog cites, the average cost of child care for two children costs more than rent in 81 percent of towns in the U.S. The Department of Health and Human services notes that child care costs should not exceed 10 percent of a family's income. However, in many areas, this cost vastly exceeds 10 percent; in Birmingham, New York, child care costs three times as much as rent, and in San Francisco, California, child care costs about half as much as rent -- a figure which, as Slate notes, takes on new meaning when it is considered that renting a bunk bed can cost upwards of 1,000 dollars. It is these exorbitant costs for what even President Obama has called a "must-have" service that is motivating many women to leave the workplace. As Slate points out, "...For a myriad of complex and intersecting reasons—cultural norms, the persistent wage gap that keeps men in business leadership positions, the likelihood of the baby’s initial primary caretaker to continue in that role—women are usually the ones who quit." In short, as women generally bring home less money than their male counterparts, coupled with social norms, they are often the ones who stay home with the children in order to avoid paying for often cripplingly expensive child care. Indeed; "Expensive child care doesn’t just keep women out of the workforce and hamper their autonomy—it sets off a ripple effect that sustains a system of income inequality, making both child-rearing and working outside the home privileges of the rich."