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President Trump's White House has the highest turnover rate in top-level positions of any administration in history, according to a new study by the Brookings Institution.

Why it matters: Turnover can lead to inefficiency on several fronts, Kathryn Dunn Tenpas, the study's author, wrote last year. For every person that leaves, a replacement needs to be hired and caught up to speed. Replacements also tend to bring their own deputies and trusted staff, which leads to a domino effect of new hires.

By the numbers: Trump's administration had turnover in 78% of its 65 most influential non-Cabinet-level positions, referred to in the report as "the A Team." (Tenpas described the methodology for determining the A Team's members.)

  • 51 of those 65 positions have had turnover.
  • 31% of those positions have turned over more than once.

The big picture: Within the Cabinet, 9 of the 15 positions have had turnover. That's more than any of the last 5 presidents.

  • The only president to come close was George H.W. Bush with 8 Cabinet changes, but that was over his entire 4-year term.

Between the lines: The turnover has been coupled with a lack of people in leadership positions across the executive branch.

  • Trump has not nominated people to fill 143 positions that need Senate confirmation, according to an online tracker by The Washington Post and Partnership for Public Service.

The bottom line: Tenpas told NBC News that the turnover situation can lead to "upheaval and chaos" within the administration, which can hinder the government's ability to operate successfully.

Go deeper: Every high-profile Trump administration departure

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