Democratic presidential candidate Amy Klobuchar released 12 years of tax returns Monday, saying "transparency and accountability are fundamental to good governance."

The Minnesota senator was the latest 2020 contender to make her returns public. The tax returns date back to 2006, when she first became a candidate for federal office.

The documents show Klobuchar and her husband, attorney and law school professor John Bessler, paid $62,787 in federal taxes on an adjusted gross income of $292,306 in 2017.

Democrats have criticized President Donald Trump for refusing to disclose his tax returns. His financial dealings also have been the subject of investigations.

Among the Democratic presidential hopefuls who've already released their returns are Massachusetts Sen. Elizabeth Warren, New York Sen. Kirsten Gillibrand and Washington Gov. Jay Inslee. Other candidates have said they plan to release their returns but have yet to do so.

Klobuchar's returns show how the couple's income has grown since she was first elected to the Senate in 2006.

At that time, Klobuchar was the lead prosecutor in Hennepin County, Minnesota's largest county, and Bessler was an attorney at a Minneapolis law firm. That year they reported $215,326 in adjusted gross income and paid $41,984 in federal taxes.

Their highest reported income was in 2015, when Klobuchar reported earning $75,000 as a writer in addition to her Senate salary. Her book, "The Senator Next Door," was released that year.

Bessler, who has written several books on capital punishment, reported 2015 income from the University of Baltimore Law School, where he is a professor, and from Rutgers and Georgetown universities.

Their adjusted gross income for 2015 was $334,406, and they paid $79,819 in federal taxes.