Shhhhh. Don't tell anyone :
Is there anyway you can add to that chart the decrease in 2002 that came after the Rats took back control of the senate. That decrease continued until the new Republican congress was sworn in 2003 after the November 2002 elections, and GW's Tax cuts were made into law as you have noted on the chart.
The proposed tax increase of Hilliarily, Kennedy, Kerry, Boxer and others stuck a knife into our post 9/11 recovery until the election of 2002 and GW's tax cuts as you have noted on the chart.
Regarding your chart...Look how someone was able to move the Dow on a downward trend between Jan 04 and the Nov 04 election, temporarily casting gloom upon what is otherwise a straight upward trend.