Nearly 325,000 people have enrolled in individual insurance plans in Washington, marking the first time in four years that group has grown significantly, according to figures released Wednesday by the Office of the Insurance Commissioner.

The numbers, reported by health insurers as of March 31, represent an increase of almost 17 percent from the total before the launch of the state’s online insurance exchange under the Affordable Care Act (ACA).

The figures include 146,000 enrolled through the Washington Health Benefit Exchange’s Healthplanfinder, and 178,891 enrolled outside the exchange. The enrollment total is expected to grow as the exchange processes late enrollments, with a final number to be released next week.

Insurance Commissioner Mike Kreidler, in a statement, noted that the goal of the ACA was to improve the market for people who buy their own insurance. “Today’s enrollment numbers clearly show we’re moving in the right direction,” he said.

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Wednesday’s numbers may undercount actual enrollments, insurance office spokeswoman Stephanie Marquis noted, because in some cases people may have paid through the Healthplanfinder, but payment information hadn’t yet reached insurers by March 31.

Approximately 278,000 people were enrolled in health plans in the state’s individual market on Oct. 1, 2013, when the exchange opened for business. Nearly all of them — about 238,000 — received discontinuation notices from insurers and had to find new coverage for 2014.

The insurance office estimated earlier this year that about 113,000 of the new enrollees would qualify for subsidies and 30,000 others would qualify for the state’s expanded Medicaid program.

But neither Kreidler’s office nor the exchange has information on whether those newly enrolled were previously uninsured.

The office has requested more data from insurers that will provide breakdowns by demographic information and county, both inside and outside the exchange. That information should be available next month.

Carol M. Ostrom: or 206-464-2249. On Twitter @costrom