In the less than three years since President Donald Trump took office, he has had no less than 28 acting cabinet secretaries—more than the 27 total employed during President Bill Clinton’s eight years in office, and the 23 over the course of the Obama administration.

Relying on acting cabinet members is not unheard of by any means; presidents often use them at the beginning of their administration or at the start of their second term while the senate goes through the confirmation process, explains Anne Joseph O’Connell, a law professor at Stanford University.

But Trump’s cabinet has been filled by more acting secretaries than any of his predecessors—especially in his second and third years in office. O’Connell highlights that Trump had five in 2018, for example, compared to Clinton’s two, and Obama’s zero at the same time. President George W. Bush had one in his second year in office.