In 1994, Harvard University employed about 10,000 people full-time. As part of their benefit package, employees had access to a low-cost/low-benefit HMO (health maintenance organization) insurance plan or a higher cost PPO (preferred provider organization) insurance plan with more generous benefits. About 18% of Harvard employees opted for the PPO plan, which cost them $361 more than the HMO plan.
In 1995, a round of budget cuts forced Harvard to reduce its subsidy for the PPO plan. That year, the PPO plan cost employees $731 more than the HMO plan, and only 14% of employees enrolled.
In 1996, Harvard subsidized the PPO plan at the same level as the year before, but the PPO plan cost employees $1,414 more than the HMO plan. Only 9% of employees enrolled. In 1997, Harvard abandoned the PPO plan altogether.
Based on the economics underlying insurance markets, what happened in the health insurance market at Harvard from 1995 to 1997? (As part of your answer, be sure to explain the changes in enrollment rates and premiums, as well as the decision to cancel the PPO plan in 1997.)