Read the article. Watch the video.
The quantitative proof? Clapper did not write a scientific paper, but Trump and all his supporters never do either, but they lie constantly. I'd rather go with Clapper.
https://artofthelie.org/
...Trump makes false and misleading claims and states untruths on an almost daily basis. A New York Times study found that President Trump made “demonstrably false statements on at least 20 of his first 40 days as President,” and “said something untrue, in public, every day for the first 40 days of his presidency.” 1 The Times study stated, “There is simply no precedent for an American president to spend so much time telling untruths. Every president has shaded the truth or told occasional whoppers. No other president — of either party — has behaved as Trump is behaving. He is trying to create an atmosphere in which reality is irrelevant.”
We know of no president in the history of the country, other than Donald Trump, who has:
Told more than 2,100 lies, false and misleading statements and untruths in his first year in office, an average of nearly 5.9 per day;
Attacked the media as an “enemy of the American people,” placing Trump in direct conflict with founders John Adams and Thomas Jefferson;
Attacked his own law enforcement and intelligence agencies;
Attacked our strongest foreign allies while embracing our major foreign adversaries;
Sided with a major adversary over the consensus views of his own intelligence agencies;
Attacked the FBI as the “worst in history,” and accused an FBI agent of “treason” for the “crime” of making negative comments about him;
Asserted an “absolute right to do what I want to do with the Justice Department,” a right Trump does not have;
Attacked the entire court system as “broken and unfair”;
Attacked judges repeatedly for decisions which he disagreed with;
Refused to divest his vast business holdings, leaving him with massive conflicts of interest and major Emolument Clause problems;
Falsely claimed that millions of individuals voted illegally in the presidential election to explain losing the popular election by nearly 2.9 million votes.
