A large number of Minnesotans have signed up for health plans this week through MNsure, state officials said Wednesday, as they released figures showing the unusually high volume of calls directed at the insurance exchange during Tuesday's open enrollment launch.

By 9 a.m. on Tuesday, MNsure's call center had received more than 50,000 attempts to call, state officials said. The comparable tally on Wednesday morning was just 1,600 — a figure that state officials said is much closer to historical norms.

Attempted calls are all those placed to MNsure — answered and unanswered. The tally of calls received by MNsure has been much smaller, numbering just 4,100 on Wednesday.

On Tuesday, DFL Gov. Mark Dayton told reporters that the MNsure call center had been targeted by robocalling just as thousands were seeking help with their health insurance options for next year. State officials say they are investigating; no update was provided Wednesday.

MNsure is an option for Minnesotans who buy individual health insurance policies. The market serves about 250,000 state residents who are either self-employed or don't get coverage through an employer.

Open enrollment in the individual market started Tuesday with state officials encouraging shoppers to buy policies early, since enrollment caps mean some options could disappear. But the start of the shopping season was marked not only by accusations of robocalling, but also a 30-minute website outage that affected key portions of MNsure plus nearly 70 other state websites.

On Wednesday, there were no website outages, according to the state's MN.IT department for information technology services. And there were no fresh accusations of robocalling.

Whereas call center waits on Tuesday averaged 34 minutes, they were down to 6 minutes on Wednesday.

"More than 8,700 Minnesotans have enrolled in health coverage in the last two days," state officials said in a Wednesday statement. "Tens of thousands of Minnesotans are shopping and comparing comprehensive health care coverage."

Minnesota launched the exchange in late 2013 to implement the federal Affordable Care Act, which requires almost all Americans to have health insurance or pay a tax penalty.

Twitter: @chrissnowbeck