This chart says it all

A rising tide sinks most boats -- except during the Clinton years, when the economy started to right itself. And things held steady when JFK was in office.

This chart is the truest measure of whether a president was liberal or conservative; the "D" and "R" labels are much less reliable indicators.

Update:  The preceding paragraph may have been foolish, since the president does not have that much impact on the economy. The choice of president does, however, reflect the prevailing zeitgeist.