FiveThirtyEight nat'l polling average with 67 days until E-Day:
2020: Biden+9.1
2016: Clinton+3.8
2012: Romney+0.6
2008: Obama+4.3
2004: Kerry+0.03
2000: Gore+4.8
1996: Clinton+12.2
1992: Clinton+5.0
1988: Bush+3.7
1984: Reagan+21.3
1980: Reagan+1.5
1976: Carter+8.9
So 80% (4 out of 5) since 2000 are wrong.
There's a correlation here, notice prior to 2000, they were 100% correct: