It said that in the weak economy, many people had dropped their insurance, leaving "fewer people, often with significantly greater medical needs, in the insured pool".
But as with any insurance, leaving people out increases the risk of arbitrary catastrophe for those not included.
"If you have pet insurance, leaving them with a friend won't invalidate your cover," says John Franklin of insurer Virgin Money.
2012-13: He pays £35,884 in income tax and £5,535 in national insurance, leaving a net annual income of £68,581.
Each year employers pay more and more for insurance, leaving less and less to pay their employees.
But forcing people to lock their entire pension fund into this insurance leaves customers exposed to other retirement risks, such as inflation, poor health or early death.
Texas and Florida refused to set up regulated marketplaces, known as exchanges, for the sale of subsidized insurance, leaving the task to the federal government.
Millions of people would have to give up insurance, leaving them without protection and the entire individual-insurance market at risk of collapse.
Income £55k 2015-16 She currently pays £11,403 a year in income tax and £4,371 in national insurance, leaving a net annual income of £39,226.
Although there could be drawbacks to that if an incident leads to the cancellation of all the insurance, leaving the holder widely exposed.
2012-13: They pay a combined £4,358 a year in income tax and £2,734 in national insurance, leaving a joint net annual income of £30,908.
