Democratic presidential candidate Sen. Cory Booker (N.J.) answers questions during a presidential forum held Wednesday by She the People on the Texas State University campus in Houston. (Michael Wyke/AP)

Sen. Cory Booker released 10 years of tax returns Wednesday, which showed he earned $1.7 million for paid speeches he gave when he was mayor of Newark.

He earned the most from his speaking engagements in 2011 and 2013, pivotal years in his rise to national stardom.

Booker’s campaign provided The Washington Post a list of the places where he gave paid speeches between 2008 and 2013, most of them at universities. He was also paid to speak by nonprofits and companies, including Google, General Mills and MetLife.

Booker (N.J.), who is the latest Democratic presidential candidate to make multiple years of tax documents public, last year reported his lowest income of the decade. He made just his Senate salary of $152,715 in 2018 and gave $24,000 to charity, which is about 15.7 percent of his income, the documents show.

In previous years, Booker earned considerably more income from speeches and, later, book royalties.

Paid speeches became a flash point in the 2016 Democratic presidential primary election after candidate Hillary Clinton was forced to defend earning millions for giving speeches to Wall Street executives.

A May 2013 USA Today article about Booker’s paid speeches says that from 2008 to 2013, Booker donated about $620,000 of the income earned from them to charity.

His newly released tax returns show his charitable giving from 2009 to 2013 at about $363,000. His 2008 returns were not available.

Most of that charitable giving came in 2013 when he gave away stock to charities in and around Newark, including the Monmouth Medical Center Foundation and the AIDS Resource Foundation for Children.

Booker was elected to the Senate in a special election in 2013. He made the highest income of his Senate career in 2015 — $554,598 — mostly from advance royalties for his book, “United,” which was released in 2016. In 2016 and 2017, his income was $466,168 and $450,073, respectively, mostly from book sales.

Presidential candidates have long voluntarily released their tax returns, but it has become a campaign issue after President Trump refused in 2016 and this year to release his.