(CNN) Small-dollar donors were key to the Democrats' success in House races in 2018, and no one benefited more than Rep.-elect Alexandria Ocasio-Cortez, who pulled off one of the biggest surprises of the midterm cycle with her upset primary victory over Joe Crowley in New York.

A new report from Open Secrets , a nonprofit, nonpartisan research group based in Washington, found that of House members and soon-to-be House members, Ocasio-Cortez had raised the highest percentage of her 2018 funds from small dollar donors (defined as individual contributions less than $200). Around 62% of the more than $2 million Ocasio-Cortez raised in the cycle came from these kinds of contributors.

The the House, @Ocasio2018 leads the way in terms of money raised from small donorshttps://t.co/oseS0egwYS pic.twitter.com/2SXDrE8tQ1 — OpenSecrets.org (@OpenSecretsDC) December 18, 2018

Rep. John Lewis, a Democrat from Georgia and an icon of the Civil Rights movement, was second on the list, raising 55% of his funds from small-dollar contributors. In third place, Rep. Devin Nunes, a Republican from California and the outgoing chairman of the House Intelligence Committee, whose high-profile defense of the Trump administration amid the Russia investigation has endeared him to supporters of the President. Nunes -- one of the top House Republican fundraisers of the cycle with $12.6 million -- raised 49% of his funds from small-dollar donors.

Seven of the ten members on Open Secret's list were Democrats, some of them in the most competitive 2018 races.

Rep. Conor Lamb, who won a high-profile special election in Pennsylvania's 18th district in March in addition to his November general election contest in the redistricted 17th district, raised 45% of his $9 million from small-dollar donors, placing fourth.

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