I’ve had some requests for data sources on debt and growth; good point. So, it’s all in the public domain. The IMF public debt database offers a downloadable spreadsheet of debt/GDP ratios going back in some cases to 1791. For GDP, the easy source for 1950 onwards is the Total Economy Database; you want the file on output, labor, and labor productivity. If you want to push further into the past, the Maddison Project has spreadsheets going back in some cases to the year 1000.
For my exercise I used the Total Economy Database; I used West German growth for pre-unification, total German growth thereafter. The data are here (xls).