Medicare Advantage enrollment is expected to increase next year for the sixth straight year, and grow to cover 32% of Medicare beneficiaries, the Centers for Medicare & Medicaid Services announced Monday.

The Medicare Advantage program enrollment is expected to increase to 17.4 million by next year. That would be up from 16.5 million in 2015, and would constitute a 50% increase in total enrollment since 2010. MA plans also will begin offering additional benefits to enrollees, including dental, hearing and vision coverage, according to CMS.

Premiums are projected to decrease slightly next year. CMS estimates the average MA premium will drop $0.31, from $32.91 in 2015 to $32.60. A majority of MA enrollees (59%) will see no increase in premiums.

Medicare Part D premiums are also predicted to remain stable over the next year. CMS credited the Affordable Care Act’s slow closure of the prescription drug “donut hole,” or a gap in coverage what the drug plan will cover for drugs. The agency estimates discounts in the donut hole saved Medicare beneficiaries saved more than $17.6 billion on prescription drugs, or around $1,706 per beneficiary, between the passing of the ACA in 2010 and July 2015