## It is the rate of change which matters

Oliver Knill, October 15, 2013

 A couple of days before a potential default, there is of course a lot of talk about US dept. What is in particular puzzling is why politicians always talk about the dept and not the rate of change of the dept. To look at this, I scraped data from here (which is a bit more updated than Wikipedia) and threw it into Mathematica. Code 2 in the first entry means Democrat, Code 1 means Republican. What is the rate of change? The figure to the right shows the US national debt from 1981-2012 (green) and its rate of change. Red (Republican) and Blue (Democrat). Since clearly the blue ones have done better with spending, the current stand-off by the red guys is particularly infuriating.

Here is the Mathematica code for the above graphics:
```A = { {2,776,1978},  {2,829,1979},   {2,909,1980}, {2,994,1981},  {1,1137,1982},  {1,1371,1983},
{1,1564,1984}, {1,2120,1985},  {1,2345,1986}, {1,2601,1987}, {1,2867,1988},  {1,3206,1989},
{1,3206,1990}, {1,3598,1991},  {1,4001,1992}, {1,4351,1993}, {2,4643,1994},  {2,4920,1995},
{2,5181,1996}, {2,5369,1997},  {2,5478,1998}, {2,5605,1999}, {2,5628,2000},  {2,5769,2001},
{1,6198,2002}, {1,6760,2003},  {1,7354,2004}, {1,7905,2005}, {1,8451,2006},  {1,8951,2007},
{1,9986,2008}, {1,12311,2009}, {2,13562,2010}, {2,15223,2011},{2,16222,2012}, {2,16738,2013} };
B= Table[A[[k, 2]], {k, Length[A]}];
S0=ListPlot[B/7,Joined->True,PlotStyle->{Green,Thickness[0.01]}];
S1=Table[{PointSize[0.02],RGBColor[2-A[[k,1]],0,A[[k,1]]-1],Point[{A[[k,3]]-1980,B[[k+1]]-B[[k]]}]},{k,Length[B]-1}];
S2=Table[{Thickness[0.01],RGBColor[2-A[[k,1]],0,A[[k,1]]-1],Line[{{A[[k,3]]-1980,B[[k+1]]-B[[k]]},{A[[k+1,3]]-1980,B[[k+2]]-B[[k+1]]}}]},{k,Length[B]-2}];
S=Graphics[{S0[[1]],S1,S2},AspectRatio->1];
Export["verschuldung.png",S,"PNG"]
```
Here are more detailed data, imported already into Mathematica here which produced the following picture: