Roughly one-third of the consumers who could get 2016 HealthCare.gov exchange plan coverage for a very low monthly net premium are choosing to buy more expensive coverage.

About 6.1 million of the people who signed up for 2016 exchange plan coverage through HealthCare.gov from Nov. 1 through Dec. 26 could have gotten the coverage for a net monthly premium of $100 or less, according to a U.S. Department of Health and Human Services (HHS) report.

Only about 4.1 million people actually ended up with plans at that net monthly premium level.

One-third of those consumers, or about 2 million, ended up paying more than $100 in net monthly premiums.

Only 2.3 million of the 5 million people who could have gotten covered for a net monthly premium under $50 ended up with coverage at that premium level. The other 2.7 million ended up paying more than $50 per month.

The members of Congress who drafted the Patient Protection and Affordable Care Act (PPACA) created the exchange system in an effort to help consumers shop for coverage from private insurers on an apples-to-apples basis, and to use federal advance premium tax credit (APTC) subsidies to reduce the amount of cash they have to pay out of pocket for premiums every month.

PPACA exchange plan issuers started providing coverage for the first time in 2014. The open enrollment period for 2016 exchange coverage started Nov. 1 and is set to end Jan. 31.

In the new HHS report, officials look only at the 8.5 million consumers who have signed up for health coverage in the 38 states that use the HealthCare.gov system, not consumers in states that have their own state-based exchange programs.

Financial problems forced some popular exchange plan issuers to suspend sales of HealthCare.gov plans after they had already applied for exchange system slots.

See also: Maine CO-OP to stop selling individual policies for 2016

It’s not clear whether the HHS analysts took plan withdrawals into account when they calculated the percentage of exchange users who had access to low-net-premium plans.

HHS officials have focused largely on net monthly premiums when talking about public exchange system performance, and they have generally given little attention to matters such as enrollees’ likely out-of-pocket costs, provider network size or the plan issuer’s reputation.

If the new HHS figures reflect active consumer decisions to pay more for coverage, rather than the effects of issuer withdrawals, they could show that a significant number of exchange plan users are considering provider networks, drug formularies, plan benefits, and issuer reputation when shopping for coverage as well as price.

That could help carriers that want a chance to charge more for higher-value coverage.

Consumers’ interest in coverage quality could also hurt issuers, if it turns out that consumers who care about factors other than net monthly premiums tend to have higher medical claim costs than consumers who are thinking mostly about the net monthly premiums and the PPACA penalty now imposed on many people who lack what regulators define as minimum essential coverage (MEC).