Could you separate the elections when there was a change of party (1912, 1920, 1932, 1952, 1960, 1968, 1976, 1980, 1992 and 2000) from those when there was no change?
While that historical chart looks favorable, the atmosphere in an election year must be favorable as well for an outcome similar to that chart to come to fruition. I cannot speak for anyone else, but I do not believe we have that so-called favorable atmosphere going into this election. For obvious reasons not all election years turn out like that chart and this year could very well be one of them...