Awesome interactive graph over the link so I'll only quote bare bones.
More than a quarter of the nearly $6 billion in contributions from identifiable sources in the last campaign cycle came from just 31,385 individuals, a number equal to one ten-thousandth of the U.S. population.
In the first presidential election cycle since the Supreme Court's decision in Citizens United v. FEC, candidates got more money from a smaller percentage of the population than any year for which we have data, a new analysis of 2012 campaign finance giving by the Sunlight Foundation shows. These donors contributed 28.1 percent of all individual contributions in the 2012 cycle, a record high.
One sign of the reach of this elite “1% of the 1%”: Not a single member of the House or Senate elected last year won without financial assistance from this group. Money from the nation’s 31,385 biggest givers found its way into the coffers of every successful congressional candidate. And 84 percent of those elected in 2012 took more money from these 1% of the 1% donors than they did from all of their small donors (individuals who gave $200 or less) combined.
This elite 1% of the 1% dominated campaign giving even in a year when President Barack Obama reached new small donor frontiers (small donors are defined as individuals giving in increments of less than $200). In 2014, without a presidential race to attract small donors, all indicators are that the 1% of the 1% will occupy an even more central role in the money chase.
The nation’s biggest campaign donors have little in common with average Americans. They hail predominantly from big cities, such as New York and Washington. They work for blue-chip corporations, such as Goldman Sachs and Microsoft. One in five works in the finance, insurance and real estate sector. One in 10 works in law or lobbying. The median contribution from this group of elite donors? $26,584. That’s a little more than half the median family income in the United States.