Mitt Romney this morning released his personal tax returns, revealing an income of $21.6 million in 2010 and $20.9 million in 2011, nearly all stemming from the his vast portfolio of investments.

During the same two-year period, Romney paid about $6.2 million in taxes at an average tax rate that hovers around 15 percent, confirming the Republican presidential candidate’s recent public statements.

Romney’s effective tax rate in 2010 was 13.9 percent. His estimated 2011 return shows a rate of about 15.4 percent.

In a call with reporters, campaign advisers and the trustee of the Romneys’ charitable foundation and trio of family trusts emphasized the candidate’s charitable contributions, saying that the amount of money Romney has given away represents roughly 16 percent of his income and is “substantially more” than the proportion given by those in similar financial situations.

Romney gave more than $4 million to charitable causes last year and $3 million in 2010, according to the filings. It was distributed via Romney’s Tyler Charitable Foundation, and goes to causes that include multiple sclerosis, the Boys & Girls Club of Boston, the George W. Bush Library and Homes for Our Troops, among others. A sizable amount also went to the Church of Jesus Christ of Latter-day Saints, of which Romney is a member.

The Romneys’ personal tax return, along with the return for a trust in Mitt Romney’s name, one in the name of his wife, Ann, another that benefits his children and the Tyler Charitable Foundation were all posted online early today.

When asked why only the 2010 filings and an estimated 2011 personal return were provided, given that Romney prepared more than a decade’s worth during the vetting process during the 2008 campaign, campaign National Policy Director Ben Ginsberg of Patton Boggs said it was an “extensive disclosure” that should satisfy “the public’s, if not the Obama opposition research” team’s desire.

“There are 26 people from the Chicago area listening in — I think that sort of sums up the state of play,” Ginsberg said, referring to the city where President Barack Obama’s re-election campaign is based.

Trustee Brad Malt of Ropes & Gray pointed out that election law does not require the Romneys to disclose the contents of the family trust — neither are beneficiaries — but they have done so anyway.

“In keeping with that spirit of voluntary disclosure, we wanted you to have those documents as well at this time,” Malt said.

Romney’s release of more than 500 pages of tax documents came as pressure mounted on the candidate to detail his vast portfolio of investments as income inequality and a stagnant economy became central issues of the presidential campaign.

The returns are all available to the public on the candidate’s website.