By Dave McKinney

CHICAGO (Reuters) - Illinois Governor Bruce Rauner reported personal income of more than $188.1 million in 2015, and 90 percent of the former private equity investor's earnings came from capital gains, according to income tax returns he released on Friday.

Rauner, a Republican, and his wife, Diana, paid federal taxes of $51.6 million and $6.9 million in state taxes in 2015. Of the total income, $169.5 million was from capital gains, though no details were released on the source of those profits.

"I believe as the good book says to whom much has been given from whom much is expected in return," Rauner said at a news conference when asked about his tax returns.

Rauner, who has led a fight against Democrats controlling Illinois' legislature in the country's longest-running state fiscal impasse, and his wife contributed $21.7 million individually to various Illinois political campaigns this year to weaken Democratic control of the state legislature and dislodge the state's long-running budget stalemate, campaign records show.

Illinois has not had a full operating budget for 17 months.

Republicans netted four seats in the Illinois House and two seats in the state Senate in Tuesday’s elections, but Democrats retained control of both legislative chambers and defeated Rauner's choice for comptroller.

A separate filing from Rauner's family's foundation showed $53.6 million in assets at the end of 2015 and $11.6 million in charitable giving for the year.

In 2014, Rauner and his wife reported $58.3 million in earnings.

Because the Rauners' assets are in a blind trust, an aide said the couple is "screened from all financial decisions" and cannot explain the increase in their income.

A spokesman for Democratic House Speaker Michael Madigan declined comment on the governor’s earnings, but a top Madigan ally said Rauner's wealth puts him out of touch with the electorate.

“I don’t know how he can claim to ever understand the problems of regular, ordinary Illinoisans,” said Democratic Representative Lou Lang.

Madigan and Democratic Senate President John Cullerton, Chicago attorneys who maintain property-tax appeal practices, do not release their tax returns.

(Reporting by Dave McKinney; Editing by Leslie Adler)