Seven of the 10 lawmakers with the most earmarks in the last congressional spending bill were Republicans, according to a new watchdog report.

The findings were made by OpenTheBooks.com, which reviewed the 7,509 disclosed earmarks amounting to what the nonprofit, nonpartisan government watchdog group found to be "$16 billion in taxpayer costs."

Now-retired GOP Sen. Richard Shelby, of Alabama, took the top spot, followed by retired Republican Sen. Jim Inhofe, of Oklahoma. Republican Sen. Lisa Murkowski, of Alaska, came in third.

The report – titled "Earmarks, The Return of the Swamp Creatures" – found that the top 3 lawmakers accounted for $1.656 billion of the roughly $16 billion in total earmarks.

Republican Sens. Lindsay Graham, of South Carolina, Bill Cassidy, of Louisiana, Susan Collins, of Maine, and now-retired Roy Blunt, of Missouri, also made the top 10. (Collins tied for 10th with fellow Maine Sen. Angus King, an Independent.)

Retiring Vermont Democratic Sen. Patrick Leahy was 8th on their list while Hawaii Democrat Sens. Mazie Hirono and Brian Schatz came in 4th.

Texas GOP Rep. Randy Weber was ranked in 6th place on the list.

Overall, congressional Republicans "out-earmarked their Democratic colleagues in 21 states including Texas, Florida, Missouri, Oklahoma, Maine, and South Carolina," according to the report.

Still, Democrats earmarked more than Republicans overall – with $9.1 billion compared to $6.4 billion for the GOP lawmakers. And a bipartisan group of legislators earmarked $476 million, the report also found.