If you go back as far as Reagan, then you have to include Carter.
I was going back to Bush I. He + Slick Willy + Bush II + BHO = 4.
If you go back to Carter & beyond, Reagan was the only break in the POS POTUS pattern. Some say Carter is 2nd worst now behind Barry, but I would contend LBJ gets that slot. Carter's damage was correctable, LBJ's Great Society social engineering sabotage continues to this day.