DES MOINES, Iowa (AP) — Iowa's Democratic candidate for governor and his wife earned just over $3 million last year from a variety of sources including capital gains on the sale of stock, income from businesses in which he owns an interest, stock dividends and payment for serving as a director on corporate boards, according to tax returns released Thursday.

Fred Hubbell, 67, a retired business executive whose family history and wealth dates to the 1800s, said he'll release his tax forms annually if he's elected governor in November.

His campaign released only portions of his federal and Iowa state tax returns and just part of an accounting of the charitable foundation that Hubbell and his wife Charlotte have established.

Specifics of income sources, deductions and other details were not made available.

The release is an act of transparency in line with previous candidates including former Republican Gov. Robert Ray and former Democratic Gov. Chet Culver, said Jeff Link, a Hubbell campaign consultant.

Gov. Kim Reynolds released 10 years of tax returns earlier this month and challenged Hubbell to do the same.

"I released for 10 and I think he should release more. What's he got to hide?" she said. "I think Iowa taxpayers and Iowans deserve to see that, and you can't just talk about transparency you need to be able and willing to do that."

Link said Reynolds broadly supports President Donald Trump and ignores his refusal to release any tax records yet pushes Hubbell to do more.

"We haven't seen any information about President Trump and for the Reynolds campaign to protest loudly about Fred Hubbell sharing his tax returns, they haven't said anything about the fact that candidate Trump refused to do it and President Trump refused to do it. It's really a double standard," Link said.

Hubbell and his wife filed a joint tax return that lists a federal adjusted gross income of just over $3 million. They gave nearly $1.3 million to charities through personal donations and a private foundation.

Their state and federal tax bill combined was $647,000.

Tax returns for Reynolds and her husband, Kevin Reynolds, show they earned $163,000 last year and paid about $28,000 in taxes. They donated $17,000 to charity.

The average family income in Iowa is just over $85,000, according to census data from 2016, the latest detailed information available. The reports also show just 4.7 percent of Iowa families have an income of $200,000 or more.

Campaign financial disclosure forms filed by Hubbell in April indicate he was paid for serving on the board of Voya Financial Services, a retirement savings firm and Macerich Inc., a real estate company. Link said Hubbell has since stepped down from the boards.

Other income was generated from stock investments, interest on certificates of deposit and checking accounts, a trust, real estate investments, retirement accounts and an ownership stake in several companies including Hubbell Realty Co. and Voya Financial Services.

Campaign documents indicate Hubbell has contributed about $2.9 million to his own campaign.