As per this July 2020 Washington Post article, Trump’s rate of false statements has accelerated through his presidency, reaching 20,000 false or misleading statements on July 9, 2020.

See below the Polifact.com scorecards (arranged in order from most to least checks end of October 12, 2020).
Note that Trump’s record is now 71% (631 of 868 checks) mostly false, false or pants on fire false. None of the others below reached 50% mostly false, false or pants on fire false; although McConnel is pretty close to 50% (45% mostly false, false or pants on fire false).

Donald Trump (868 checks: 13% true or mostly true; 13% half true; 55% mostly false or false; 16% pants on fire; so a total of 71% or 631 statements that were found to be mostly false, false or pants on fire false)

Obama (604 checks: 47% true or mostly true; 26% half true; 22% mostly false or false; 1% pants on fire; so a total of 23% or 151 statements that were found to be mostly false, false, or pants on fire false)

Hillary Clinton (300 checks: 49% true or mostly true; 23% half true; 24% mostly false or false; 3% pants on fire; so a total of 27% or 83 statements that were found to be mostly false, false or pants on fire false)

Joseph Biden (144 checks: 36% true or mostly true; 23% half true; 34% mostly false or false; 3% pants on fire; so a total of 37% or 64 statements were found to be mostly false, false, or pants on fire false).

Mitch McConnell (37 checks: 36% true or mostly true; 18% half true; 42% mostly false or false; 3% pants on fire; so a total of 45% or 15 statements that were found to be mostly false, false or pants on fire false)