RIVERHEAD, New York — Mitt Romney's campaign released the latest two years of tax returns for Paul Ryan, showing his running mate paid a 15.9 percent tax rate in 2010 and a 20 percent rate last year.

The policy of releasing two years of tax data dovetails with Romney, whose refusal to release pre-2010 returns has been repeatedly criticized by Democrats as he tries to unseat President Barack Obama in November's election.

According to copies of tax returns filed by Paul and Janna Ryan and released by the campaign at the tail end of the weekly news cycle, the couple paid $64,764 in taxes on $323,416 of adjusted gross income in 2011, for a tax rate of 20 percent.

In 2010, they earned a total of $215,417 in adjusted gross income and paid $34,233 in taxes, for an effective tax rate of 15.9 percent.

The Romney campaign has been eager to put the issue of his personal taxes to rest, but the Obama re-election team has been hammering Romney's refusal to release more returns, saying it only raises questions about the candidate's business and financial history.

A two-year release by Ryan is not unexpected. Should he have released many more years of returns, that could have further raised suspicions that Romney was hiding something in his financial history.

Democrats have sought to tar Romney as a wealthy elitist with no sympathy for the common man. He has proposed cutting income tax rates by 20 percent, eliminating tax on investment income, and slashing the corporate tax rate.

Obama has said such a proposal would hike taxes on families with children by $2,000 to pay for Romney's $5 trillion tax plan, which would mostly benefit the wealthy.

Obama's team made a surprise offer to Romney on Friday -- that if he were to release five years worth of tax returns, they would stop asking about the other five. The Romney camp declined.

On Thursday, Romney said he has paid a tax rate of at least 13 percent in each of the last 10 years, but the White House hounded him to prove it.

Romney -- currently on Long Island, New York where he was attending two fundraisers -- paid an effective tax rate of 13.9 percent in 2010, according to returns he has released, as his income from investments was taxed as a capital gain rather than under the higher rates applied for salaried income.

The current highest US income tax rate is 35 percent.

Photo: Flickr user Gage Skidmore, creative commons licensed.