There were 3 articles of impeachment drafted against him so that's probably the number to go with. Never got tried in the Senate because he resigned, never got prosecuted because he was pardoned.
However...the pardon was for "any crimes he might have committed" and per Burdick v United States an accepted pardon is a confession of guilt so technically Nixon has confessed to an unlimited number of crimes.
For a second I thought you were making an anti-biden post. With the (unfounded) implication being that Biden should be next to trump. Then I looked, and he's not at the bottom either. They only have 44 total. Biden would be 46. So one other president is missing too.
What did he ever do for America? What, because he was instrumental in the alied victory in Europe, spearheaded the national highway system and oversaw desegregation that he deserves some kind of medal?!
They're both issues, but only the latter is a prosecutable offense in our current legal system. They should both be, but that's not the current state of the law.