One of the most buzzed-about moments of former FBI Director James Comey's testimony in front of the Senate Intelligence Committee was the questioning of Sen. John McCain (R—Ariz.), which left both Comey and viewers deeply confused.

In addition to referring to the former FBI Director as "President Comey" on multiple occasions, McCain also questioned why the FBI didn't investigate Democratic presidential candidate Hillary Clinton for colluding with Russia—even though no such allegations exists, and multiple intelligence agencies have asserted the Russia hackers were committed to releasing information that would harm Clinton.

It's impossible to know if McCain's confused line of questioning is a result of his advanced age or just the product of a bad night's sleep, as he suggested.

However, the fact that so many jokes are being made at the expense of a sitting senator reveals a deeper problem with the United States Congress, and in particular the Senate: the fact that so many elected officials are much older than the people they represent.

McCain is 80, and is not even the oldest member of the Senate. Dianne Feinstein holds that honor at 83, and she and McCain are two of 11 Senators that are over the age of 75.

In fact, according to data blog Quorum, the Senate is one of the oldest in history, with an average age of 61. Well over half of the senators up for re-election in 2018 and 2020 are over age 65. However, it's even the oldest Senate in history; the one seated 2009 averaged 63 years old.

The average age of the Senate Intelligence Committee members is 62, with just three (Republicans Marco Rubio, James Lankford and Tom Cotton) under 50.

By contrast, the median age of an American citizen is 37.8, and not a single senator is younger than 40. Because incumbents are extremely hard to unseat, and seniority conveys enormous privilege in Congress, few seats held by older members turn over.

The advanced age of Congress creates a disconnect between them and their constituents. According to Qurorm's data, "1/3 of [member of the House of Representatives] over 60 represent districts with a median age of 35 or less."

"There are 44 congressional districts in which the age of the Representative is more than double the median age of their constituents. Of these 44 Representatives, 38 won their last election by more than 60 percent of the vote," the report continues.

In its 2013 analysis of the age gap between members of Congress and their constituents, Slate adds that "Congress is decidedly older than the populace it represents. ... 22 percent of the general population and 30 percent of registered voters are between 25 and 39 years old. The average American is more than 20 years younger than the person who represents him or her in the House."

This will become even more of a problem as millennials become the largest voting block, which could happen as soon as the 2020 presidential election, according to data from Pew.

Other data from Pew indicates a wide gulf in the importance of issues between older and younger voters, as older voters are much more concerned with social security and the Supreme Court; and younger voters focused more on minority rights and treatment of the LGBT community.