The longest time series are those for central government debt as a percent of GDP. There are numerous countries where scholars have not yet constructed reliable nominal GDP series to fill in the gap prior to the official statistics (which often only begin post 1900 and are reported in Mitchell's comprehensive regional reference books-see references). In these cases, where we have the public debt data (but no nominal GDP), we report debt-to-export ratios, as trade data usually spans earlier periods. We then report both two series: debt to exports (based on available data as well as a backcasted debt-to-GDP data based on historic ratios of exports to GDP (over periods where both time series are available). In all cases, we note the periods for which the backcasting is done. There are a handful of cases where careful country studies have constructed long time series for general (rather than central government) debt (the studies for Italy from 1861 and the Netherlands from 1816--see listed references stand out in this regard), so we report these series in lieu of central government. These exceptions are duly noted and documented. Finally, there are several emerging markets where it is possible to reconstruct external public debt from the extensive documentation on external bond issues (usually early to late 1800s); these longer time series on external debt are reported separately and referenced accordingly.

Four spreadsheets cover annual data from as early as 1692 for the UK and 1719 for Sweden (depending on the country) to 2010 (updated with the World Bank's July 2010 Quarterly External Debt Statistics and individual mostly official country sources, as detailed for public debt) for 70 countries. Each country has its own page with the underlying data from multiple sources (with their corresponding full bibliographical references) that make up the Reinhart-Rogoff (RR) series that are reported.