They are now on the campaign Web site. GOP VP nominee Rep. Paul Ryan paid an effective tax rate of 15.9 percent in 2010 and 20 percent in 2011.

A little over half that income comes from Ryan's salary.

Like Mitt Romney, Ryan has agreed to release only two years of tax returns.

Ryan's overall assets are worth between $2 million and $7.7 million, according to his financial disclosure statements.

The Milwaukee Journal-Sentinel has a deeper dive into Ryan's investment income, much of which comes from his wife's holdings.

"As these are properties Rep. Ryan 'married into,' for lack of a better term," Ryan spokesman Kevin Seifert told the paper, "he does not play an active role in them and has no plans to."

Romney paid an effective tax rate of 13.9 percent in 2010 and estimated an effective tax rate of 15.4 percent in 2011. The Republican nominee told reporters this week that he has never paid a rate of less than 13 percent.