Amid allegations by college students that school health insurance is skimpy, Massachusetts regulators have proposed that colleges start tracking how many students rack up annual medical bills beyond what their policies cover. Under the proposal, colleges would be required to report to state regulators information such as the number of times insurers refuse to pay for student injuries or illnesses; the number of grievances students file against the companies; and the percentage of profits the companies apply toward students' medical services. Regulators said the proposal would be a first step as they consider whether to make insurers offer student plans that provide more generous benefits.