CHATTANOOGA, Tenn. (AP) — Tennessee’s biggest health insurer has proposed raising premiums next year by an average of more than 36 percent.

The Times Free-Press reports BlueCross BlueShield of Tennessee lost $141 million during its first year of offering individual health plans through the federal Affordable Care Act.

The insurer says it initially underestimated the number and cost of the medical claims filed by new enrollees.

BlueCross Vice President Roy Vaughn says the insurer’s mission was to serve the entire state as affordably as possible under the Affordable Care Act.

Last year, the insurer enrolled nearly two-thirds of the 231,000 Tennesseans who signed up for health insurance exchange plans last year.

The deadline for state regulators to make a decision about the proposed rate hikes is August 25.

If approved, average individual rates would rise to more than 60 percent above their 2014 levels.