[outofsalt]

Thank you! I have wanted this sort of material for a long time.
You should publish this along with a narrative format to tie it all together. Some thing which lists each president and who controlled each house during their tenure and the yearly changes. Something like, “Bill Clinton's first two years were dominated by democrats in both chambers and it wasn't till the Republican revolution that the budgets were balanced.” Or, “Ronald Reagan's terms were hampered by democrat...”
I would pay for such an article maybe someone else would too.

[CodeToad]

Unfortunately, I do not know the narratives as to why spending increased or decreased. There is little to go on other than news reports that are themselves biased and inaccurate.

I am letting the numbers speak for themselves. We cannot go back in time and try to conclude why a budget was more or less; we can only say that it was. Attempting to rationalize spending is extremely difficult and horribly inaccurate. What political pressures were exerted is unknown, as everything from personal political views to political lobbyists play heavy in all political actions, and those activities are simply unknown.