Writing at Politico, former Bill Clinton adviser Doug Sosnik argues that one reason Congress isn’t holding Trump accountable for his actions is that there’s been a decline in seniority on the Hill in recent years and, therefore, less of a sense of the importance of preserving congressional institutions.

“During Clinton’s impeachment trial, we worried not only about Senate Republicans but also Democrats, especially [former West Virginia senator Robert] Byrd, who was adamant that the Senate not yield its constitutional authority merely because the president of the United States was a fellow party member,” Sosnik writes. “Trump, however, does not have any Robert Byrds to fight.” After 2008 and 2010, he says, the Senate lost more than 500 years of experience.

It’s true there has been a recent decline in seniority in Congress. But it’s a relatively small decline after seniority in Congress hit a high.

“Years of service” is a little murky: If someone comes in midyear, how is that counted? Does tenure in the House count as seniority in the Senate?

Using data compiled by GovTrack, we tallied the total number of days of service for members of the House and Senate in each year of American history. (The answer to the two questions above, then, are “as about 180 days” and “yes.”) The result looks like this:

(The first year of each Congress includes outgoing members who generally have much more experience than the incoming freshman class; hence the spike/drop pattern above.)

Yes, there was a decline after the 2007-2008 Congress. But things are now at about the same level in the Senate as they were two decades ago. That happens after big shifts on Capitol Hill. It happened after Republicans dominated in House and Senate races in 1980; it happened in the House after 1994. Boot out a bunch of incumbents, and, no surprise, you lose seniority.

Look at it another way: Here’s the percentage of senators with at least 10,000 days of experience — about 27 years — in each year. The number has dropped — but it’s still higher than at any point before 1967.

In fact, there’s a higher percentage of longer-serving senators now than when Clinton was facing impeachment.

Perhaps, then, the lack of respect for congressional institutions is a function of the coverage of what’s happening on Capitol Hill. Perhaps congressional leaders aren’t being held to account by reporters who are too young to respect how things used to be done.

Well, that’s probably not the case, either. While data on the age of journalists is hard to come by, a 2013 report from the Indiana University School of Journalism continued a four-decade tradition in which the demographics of reporters was tracked. This isn’t only political reporters, but the trend since the early 1980s is consistent: On average, journalists are older than they used to be.

What is unique in recent years is the “emergence of a newly rigid partisanship,” as Sosnik puts it. Partisanship data from VoteView makes clear that the one unqualified trend in the past several Congresses has been movement away from the middle and toward partisan poles — especially among members of Trump’s party.

It’s hard to say how a Robert Byrd would have behaved toward Clinton had he been serving during a moment when his party generally was behaving in a much more sharply partisan fashion than it had been a decade or two earlier.

It’s impossible to compare now with then, not because those long-gone days had longer-serving senators, but because those who are serving are much more likely to hold strongly partisan viewpoints. Which is precisely the criticism that Sosnik’s argument would have appeared to be trying to soften.