(CNN) He's had three national security advisers, three chiefs of staff and three attorneys general and he hasn't even been in office for three years. One other result of the chaotic churn in President Donald Trump 's Cabinet is that he has fewer women -- down to just three.

Homeland Security Secretary Kirstjen Nielsen was forced out over the weekend because her boss wanted a more hardline immigration policy. The repercussions of her departure have already led to what one source described to CNN's Kaitlan Collins as a " near-systematic purge " at the agency that oversees immigration and the nation's borders, among many other things.

It comes after the announcement less than two weeks ago that Small Business Administrator Linda McMahon is leaving her position to join Trump's outside political group . McMahon, who made a fortune as the executive in charge of the WWE, which at one point featured Trump, will stay in his orbit as she tries to raise money for the super PAC that will try to help him win reelection.

The current commissioner of Customs and Border Protection, Kevin McAleenan, will temporarily take on the duties of homeland security secretary. It's not clear who will take over for McMahon.

They were preceded by UN Ambassador Nikki Haley , whose position has gone unfilled since her departure months ago.

Depending on who permanently replaces Nielsen and McMahon, Trump will have just three women sitting at the table for Cabinet meetings. Haley's UN position -- one that has been filled by a succession of women -- was downgraded, leaving 23 Cabinet-level positions.

Counting the vacated roles, that leaves women as just 13% of Trump's Cabinet-level officials, a lower percentage than either Barack Obama or George W. Bush and the lowest in decades , according to the Center for American Women and Politics at Rutgers.

It's not clear that the remaining women in Trump's Cabinet are in any danger, though Education Secretary Betsy DeVos has been under scrutiny recently for her department's short-lived proposal to cut funding for the Special Olympics, which briefly put her on the wrong side of Trump. Transportation Secretary Elaine Chao -- the wife of Senate Majority Leader Mitch McConnell -- and CIA Director Gina Haspel, Trump's replacement for his now-Secretary of State Mike Pompeo, are the other two.

Turnover in top positions

But the shrinking number of women in Trump's Cabinet is just one symptom of the remarkable changeover among his top staffers, something that's been chronicled throughout his presidency . He's had five communications directors, for instance, which is not a Cabinet-level position but has been a central role for previous White Houses. That position is currently vacant, essentially filled by Trump and his Twitter feed.

There is also not currently a permanent chief of staff, supposedly the president's right hand, and a position that does not require Senate approval, although it does have Cabinet rank.

Reince Priebus came first, the Republican insider who lasted a little more than six months in the role. John Kelly lasted longer, a year and half, from July of 2017 through the end of 2018. Rather than give his successor the title outright, Trump made Mick Mulvaney, who is still technically the director of the Office of Management and Budget, a sort-of promotion to acting chief of staff. A deputy of Mulvaney's is now acting OMB director.

Acting leaders

And that's another key theme of Trump's presidency. He'll fire or push out a Cabinet secretary who frustrates him and then wait months to nominate a permanent successor, even in crucial roles.

That's what happened with Attorney General Jeff Sessions, the nation's top lawyer. Trump pushed Sessions out of the role after more than a year of venting his frustration that Sessions had recused himself from the Russia election interference investigation. The President waited a month to nominate William Barr in Sessions' place.

At the Pentagon, Patrick Shanahan has been acting secretary of defense for nearly four months and it's still not clear if Trump will nominate him as a permanent replacement

Turnover in national security, diplomacy positions

Shanahan isn't the only key national security official to be left hanging.

Working closer to the President on a daily basis is his national security adviser, which is also not a Cabinet role but is key to national security policy. Trump's had three. Michael Flynn was fired after he lied to Vice President Mike Pence. H.R. McMaster left after policy disagreements with the President. Now in the role is John Bolton, a foreign policy hawk who has disagreed with Trump on Syria.

Nielsen herself had been on thin ice with Trump for months even though she had defended his controversial positions, like separating the children of undocumented immigrants from their parents at the border. She had been brought to the role by her predecessor, Kelly, a former Marine who left his position as homeland security secretary to become Trump's second chief of staff, before being supplanted by Mulvaney.

Trump has already had more turnover among his Cabinet in a little more than two years than recent presidents have had in four years, according to research by Brookings. That turmoil extends to top staffers in government who are outside the Cabinet. On the website outlining top leadership for the Department of Homeland Security , for instance, which is the umbrella agency in charge of everything from border policy and immigration enforcement to the Federal Emergency Management Agency and the Secret Service, there are 14 "acting" or "vacant" positions. And that's not including Nielsen or Secret Service Director Randolph Alles, who are on their way out.