While the base pay for members of Congress is $174,000, nearly half — 261, to be exact — are millionaires, according to an analysis of 2009 data from the Center for Responsive Politics (there are 535 total members of the House and Senate). Just 1 percent of Americans overall can say the same.

While the economy has generally faltered over the past two years, congressional members actually saw their collective personal wealth increase by more than 16 percent between 2008 and 2009, according to the study, which analyzed financial disclosure data released earlier this year.

According to the Center's estimates, the wealthiest member of Congress is Rep. Darrell Issa (R-Calif.), whose holdings exceed $303.5 million. Rep Jane Harman (D-Calif.) is close behind with $293.4 million, and Sen. John Kerry (D-Mass.) rounds out the top three at $238.8 million.

Members of Congress are only required to report their wealth and liabilities in broad ranges, so the Center calculated each member's average estimated wealth by determining the minimum and maximum value of their assets. Additionally, federal financial disclosures don't require members of Congress to report certain assets such as personal residences.

The list of Congress' wealthiest members is bipartisan. In the House, five Democrats and five Republicans make up the 10 wealthiest members, while in the Senate, six Democrats and four Republicans make up the top 10.

The median wealth of a House member in 2009 stood at $765,010, while the median wealth for a senator in 2009 was nearly $2.38 million.

Members of the House and Senate made investments last year in a number of companies that have a strong presence on Capitol Hill, spending large sums on lobbying efforts and political donations. The most popular company among members of Congress, CRP found, was General Electric, in which 82 current members invested. The second most popular company was Bank of America, which 63 members invested in.

The CRP's report comes as Congress considers what to do about the Bush tax  cuts, which are set to expire at the end of the year. President Obama has long advocated for extending the tax cuts for everyone except individuals making over $200,000 or families making over $250,000 — the top 2 percent of income earners. Republicans and some moderate Democrats, however, want to extend all of the tax cuts, and the White House has signaled it is willing to compromise to a degree on the matter.

Stephanie Condon is a political reporter for CBSNews.com.

Center for Responsive Politics: Why does this matter?

By May 15 of each year, congressional members, key staffers and top officials in the executive branch must file forms covering the preceding calendar year that detail their personal finances. By law, they must list their assets and liabilities, their income (excluding their government salaries, oddly), asset transactions, gifts they received and more. They need not list property unless it produces income, meaning their primary residence is generally not listed. They must include the source of their spouse's income, but need not report the amount.

Why should Americans care about the personal finances of their federal lawmakers? There are several key reasons:

Thousands of companies and special interests groups have business before Congress each year or lobby Congress directly. Some of these businesses may also find themselves the targets of congressional scrutiny for questionable business practices, accidents, even disasters. All the while, lawmakers themselves sometimes have stock holdings or other financial relationships with these corporations and associations, raising the specter of conflicts of interest.

About 1 percent of all Americans are millionaires. In Congress, that number regularly hovers between 40 percent and 50 percent, meaning elected leaders generally need not worry about the economic pressures many Americans face – from securing gainful employment to grappling with keeping a family financially afloat. Decide for yourself if these congressional millionaires are adequately representing your financial interests.

Congressional members' personal wealth keeps expanding year after year, typically at rates well beyond inflation and any tax increases. The same cannot be said for most Americans. Are your representatives getting rich in Congress and, if so, how?

Personal financial disclosure reports tell you a lot, but not everything. For example, they're only filed once every year, meaning the information contained may already be stale the day it’s made public. Likewise, lawmakers are only required to disclose their assets in broad ranges, meaning a truly accurate snapshot of a lawmaker's wealth is difficult to ascertain. Legislation has been already put forward to improve disclosure. Contact your member of Congress and let your voice be heard if you don't consider this level of disclosure adequate.

Further complicating matters: Members of Congress file their personal financial disclosure reports on paper, not by computer. This reduces their timeliness and makes analyzing the documents significantly more challenging than it would otherwise be.