The U.S. ambassadors appointed by President Trump have given more financial support to his election than any cohort of ambassadors in recent history, even as they demonstrated fewer qualifications for the job, according to a new study of ambassadorial appointments over the last three decades.

Expand chart Data: Scoville, 2019, “Unqualified Ambassadors”; Note: Dollar values are adjusted for inflation as of July, 2017; Get the data; Chart: Harry Stevens/Axios

Why it matters: The data undercuts Trump's campaign claim that his personal fortune places him above the influence of donor cash — and shows how campaign contributions can help secure jobs for people with relatively weak diplomatic backgrounds.

By the numbers: On average, Trump-appointed ambassadors contributed $96,927.98 to his campaign and supporting entities, such as independent expenditure committees, according to the forthcoming paper by Marquette University Law School's Ryan M. Scoville.

Trump's ambassadors' average contribution far exceeded the previous record of $60,721.83 set by George W. Bush's ambassadors.

far exceeded the previous record of $60,721.83 set by George W. Bush's ambassadors. Meanwhile, just 58.6% of Trump's appointees were career Foreign Service Officers, a record low among presidents since Ronald Reagan.

Scoville's paper is based on more than 1,900 certificates of competency — documents the president is legally required provide to Congress for each ambassadorial appointment. He obtained most of them from the State Department under the Freedom of Information Act.

In addition to experience in the Foreign Service, Scoville compares presidents' ambassadorial appointees by how familiar they are with their host countries, an area where Trump's ambassadors fare somewhat better.

Key data points:

Among ambassadors chosen from outside the Foreign Service , the average contribution to the president who nominated them was about $88,135. Among career Foreign Service Officers, by contrast, the average contribution was only about $31.

, the average contribution to the president who nominated them was about $88,135. Among career Foreign Service Officers, by contrast, the average contribution was only about $31. Of the 207 ambassadors who contributed at least ten thousand dollars , only one — Todd D. Robinson, whom Barack Obama appointed ambassador to Guatemala in 2014 — was a career Foreign Service Officer.

, only one — Todd D. Robinson, whom Barack Obama appointed ambassador to Guatemala in 2014 — was a career Foreign Service Officer. The largest financial contribution to any president came from the late Roland Arnall, who gave nearly $9.5 million to George W. Bush's campaign and a handful of pro-Bush committees and independent expenditure groups. Arnall served as ambassador to the Netherlands from 2006 to 2008.

The big picture: Though favored by presidents, America's preference for selecting ambassadors from outside the professional diplomatic corps is rare among advanced democracies and is opposed by the U.S. Foreign Service's professional association.