An Annotated Timeline of U.S. Public Debt, using Google Spreadsheet and Google Calendar

The Guardian have posted a list of data they've compiled from various public sources and placed in Google Spreadsheets for anyone to use.

I'd been working with Google's Visualisation API recently, so thought I'd take one set of data in a Google Spreadsheet (U.S. National Debt) and combine it with another set of data in a Google Calendar (History of the United States, taken from Wikipedia) to make an annotated timeline.

See it here: A graph of U.S. Public Debt over time (since 2001).

(I know, there's not much annotation, but the data's over such a short time-scale there didn't seem much point).