PwC's announced averages are based on all individual plans that will be sold either on the Obamacare exchanges or in the open market. The company said it found no significant distinction between those two submarkets. More than 35 million Americans are covered by individual plans they buy for themselves or have bought by family members, as opposed to the 170 million or so covered by employer-based plans.

Still, consumers need to be cautious when shopping for a plan. While the average proposed price increase is moderate, there's "wide variation" in the percentage increases sought by individual insurers, Connolly said. "There are some very high ones," she said.

"Colorado has approved premiums that range from a decrease of 22 percent to an increase of 35 percent," Connolly said. However, the average price increase is just 2 percent in Colorado, which has finalized its 2015 rates.

The wide variation in the individual market reflects, in part, a change in tack by some insurers after their first year selling Obamacare plans.

"Some players went into this last year with different strategies," Connolly said. "Some went in intentionally with very low prices because they wanted to capture market share. ... On the other hand, there were some that were a little uncertain about this new market" and priced their plans higher than they are now, she said.

'Informed guesses'

Regardless of their strategy for the first year, all insurers who are selling plans in 2015 were forced to set proposed prices with little-often very little-knowledge of how their customers in 2014 would use their new benefits during the year.
 

Nearly half of the more than 8 million people who selected exchange-sold plans this year did so in March and April, right before the end of open enrollment. Insurers began setting proposed rates just several months later, in June, leaving little time to collect meaningful information about customers going to the doctor or hospital, or buying prescription medication with their insurance.

"Last year's rates were almost entirely guesswork, because it was a brand-new concept," Connolly said. "As for 2015, the rates, I would describe them as informed guesses."

Connolly said she expects insurers are viewing the Obamacare exchanges as an opportunity to boost revenue, which is why there is a net increase in the number of issuers of plans this coming year. "That speaks to the growth opportunity that issuers are seeing," she said.

One of those new issuers is Physicians Health Plan, the insurance arm of a community health system in Lansing, Michigan, called Sparrow Health.

 PHP, which already sold employer-based plans and Medicaid plans, stayed out of the Obamacare market last year in part because of uncertainty about it, as well as the need to deal with other issues first, according to Dennis Reese, the insurer's interim CEO.

"We were prepared to file [rates] last year, and in fact we did all the preparation, and then in the end we determined we are not going forward," Reese said.

But PHP decided to join HealthCare.gov, the federally run market that serves Michigan and 37 other states, this year. The insurer will be offering 12 separate health plans in eight Lansing-area counties.

"We believe that the exchanges are the wave of the future," Reese said. "We determined that we definitely need to be in the exchange, and it looks like it's going to stay, in some form."

Reese said PHP's premiums are higher than some competitors and lower than others. Michigan residents overall are faced with proposed Obamacare rate hikes of just 0.2 percent, on average, according to PwC.

But Reese said, "I think it's too early to tell" whether Michigan, or other states, will continue to see moderate average price increases in the future.

One reason was "the rates had to be put in before there was really any sound experience on what to base those rates on," Reese said, echoing Connolly. "Right now, it's people's best estimate."

But if those premiums aren't high enough to cover the costs of benefits paid out to enrollees, insurers will have to raise them in coming years, possibly by a much greater amount than they did for 2015.

Another reason rates might rise significantly higher in the future is that two out of the three Obamacare programs that are designed to financially protect insurers from the risks of enrolling too many sick people and not enough healthy people are set to expire after 2016.

Once those programs and the monetary cushion they provide go away, some insurers might be compelled to increase premium prices more aggressively than their competitors.

"That all has to be played out," Reese said.

But he noted that the current presence of those risk-protection programs is one of the reasons that PHP expects it is important to get on the Obamacare exchange now instead of later.