The following graph shows the deficits/surpluses in terms of GDP since 1970:
The actual numbers and sources can be seen at http://home.att.net/~rdavis2/def06.html. The gray line shows the commonly reported "unified deficit", the green line shows the deficit including the funds being borrowed from Social Security, and the red line shows the deficit including the funds being borrowed from all of the trust funds. As a percentage of GDP, GW Bush is not running the largest deficits. However, he is running a close third behind Reagan and his father.
To be fair to GW's father, he inherited a large deficit from Reagan and that deficit got only slightly worse going into the 90-91 recession. The largest increases in the deficit occurred under GW (2000-03), Reagan (81-83), and Johnson (74-76). The largest decrease in the deficit was clearly under Clinton.
Still, a much better measure of our financial health is the DEBT as a percentage of GDP. It is the debt, not the deficit, that we and our children will have to pay interest on forever. The following graph shows the latest CBO projections for the debt as a percentage of GDP:
The actual numbers and sources can be seen at http://home.att.net/~rdavis2/cbobud05.html. If the tax cuts and the fix of the AMT (Alternate Minimum Tax) are extended, the debt is projected to increase from the current 64 percent of GDP to 81 percent of GDP by 2015. Then the Boomers start to retire and our finances really get interesting (see http://home.att.net/~rdavis2/pro2006.html.