If confirmed as secretary of the Department of Health and Human Services after his Senate confirmation hearing on Wednesday, Alex Azar will be the newest member of Donald Trump’s Cabinet, which has been less stable than the first-year Cabinets of any president since 1977.

Back in the simpler times of August, I measured the retention rate of Trump’s top advisers — anyone with the title of “assistant to the president” — and found that even though Trump’s advisers were departing unusually quickly, it was too soon to say whether it was out of line with historical trends. But after Trump’s original secretary of health and human services resigned — the third departure from his Cabinet since he was sworn in in January — I wondered about that group specifically. Are the moves among Trump’s top advisers and federal department heads unusual? My analysis of high-level replacements since Jimmy Carter’s first year in the White House found that Trump is the only recent president to have any replacements in his first year.

To measure Cabinet turnover, let’s first be clear on who we’re talking about. A president’s Cabinet is made up of the vice president, the secretaries of the congressionally approved Cabinet departments — for example, the secretary of defense, who heads the Department of Defense — and any other top officials the president declares to be “Cabinet-ranked.” It’s at the president’s discretion who is counted in this “Cabinet-ranked” group, although some roles are routinely included (for example, the White House chief-of-staff position has been a part of the Cabinets of Trump and former Presidents Barack Obama and George W. Bush).

In February, Trump announced 24 total positions for his Cabinet: In addition to the vice president and the secretaries of the 15 current U.S. Cabinet departments, he selected eight other officials, including the director of the CIA and the administrator of the Environmental Protection Agency. For my turnover analysis, I compared changes in Trump’s Cabinet to changes in the same positions for presidents going back to Carter. For all presidents except Trump, I counted the number of replacements who were confirmed by the Senate during each year of a president’s administration, excluding the first official in each position. For example, in 2011, President Obama replaced his original defense secretary, Robert Gates, with Leon Panetta, which counts as one replacement in Obama’s third year in office. For Trump, I’m counting departures alone because two of the vacated positions don’t have confirmed replacements yet.

According to this methodology, Trump’s loss of three Cabinet members so far gives him the most turnover in the first year of a recent presidency. For Trump, the changes started with the departure of his first chief of staff, Reince Priebus, in July (No. 1). Priebus was in turn replaced by John Kelly, who had to leave his position as the secretary of homeland security (No. 2) to take the job. Finally, Tom Price resigned in September from his post as health and human services secretary (No. 3). Neither Kelly nor Price has officially been replaced yet, though, if confirmed, Azar will replace Price.

One quick note on this methodology: Obama is the only other president in my analysis who started his first year in office with all 24 of the positions in Trump’s Cabinet (although, confusingly, Obama did not include all 24 of those positions in his Cabinet). For example, the Department of Homeland Security — one of the 15 current Cabinet departments — did not exist until 2003. This means that for many of the pre-Trump years, my analysis considered turnover in a slightly smaller number of positions than 24.

We can learn a few more things from this analysis. First, if we look across the presidencies before Trump, there hadn’t been an upward trend in Cabinet turnover — it’s actually quite common. Carter and George H.W. Bush, both one-term presidents, had 14 and 11 replacements, respectively. Two-term presidents had commensurately more.

What’s not common is so much change so early in a term. For two-term presidents, turnover generally crept up a few years into an administration and then jumped — predictably — at the start of the second term. Before Trump, only one president since 1977 had had a departure in the first year of his presidency. Bert Lance, Carter’s first director of the Office of Management and Budget, resigned amid a financial scandal (he was later cleared of wrongdoing). However, he wasn’t formally replaced by James McIntyre until March of the following year. The next-closest case is the resignation of President Bill Clinton’s first secretary of defense, Les Aspin. It was announced in December of Clinton’s first year, but Aspin didn’t leave the job until early in Clinton’s second year.

I also compared retention rates for Cabinet-level staff across the positions themselves. The White House chief-of-staff post has been the most volatile. Over the four two-term presidents in my analysis, there were a total of 11 replacements of the chief of staff. Among one-term presidents — Carter and the first President Bush — the chief-of-staff position is the only position that was replaced twice. This may be in part because the position doesn’t need to be confirmed by the Senate, so replacements can be made more easily.

One might argue that it’s not fair to compare Trump’s turnover to turnover in roles that weren’t considered part of the Cabinet by other administrations. But there is no formal, reliable list of who was officially Cabinet-ranked for presidents before George W. Bush, so it’s not possible to review only the change in positions deemed Cabinet-level by each president.

It’s important to note that we do not know whether staff turnover is inherently a bad thing. Although it sounds potentially chaotic or turbulent, it may also be evidence of learning or adaptation. As with the adviser analysis I did this summer, it’s too soon to tell whether Trump is going through these shake-ups more frequently than his peers or just earlier. If Trump is merely moving faster with his shake-ups but ends up with the same number of changes as other presidents, things will calm down; otherwise, we’re just getting started.