Assume that health insurance is private in a country, and the market for insurance is competitive. The figure below shows the marginal benefit and willingness and ability to pay curve. Premium (thousands of dollars per year) 121 10 8 6 2 10 D = MB 20 30 40 Quantity (millions of families insured) Suppose that the marginal social benefit of insurance exceeds the willingness and ability to pay by a constant $2,000 per family per year. Suppose the marginal cost of health insurance is a constant $8,000 a year. What is the efficient quantity of health insurance policies