Comparing the 25 presidential elections of the 20th century*, Dukakis had the 11th best percentage (not margin) for a Democrat. Better than every other losing Democrat, better than Wilson 1912 and Clinton 1992. He is in the top half.
* I consider that the election of 1900 belongs to the 20th century and the election of 2000 belongs to the 21th century, because in 1900, a president was elected for a term starting in 1901 and finishing in 1905, so, in the 20th century.
Better than the 1912 and 1992 elections, too, but vote percentage isn't the only thing that counts.