The US Census Bureau has made its database of economic indicators searchable.
You can even download data for further manipulation, although I must admit being bemused by the “Download straight from website to Excel.”
I wonder if they mean “Excel” in the sense of any old spreadsheet program like people who say “photocopy” by another name, that starts and ends with an “X?” 
Probably not. They probably mean a specific bit of software.
Thought I would mention it as one of the many data sources from the US government that can be re-purposed for use with a topic map.
I am sure other governments make similar data sources available.
If you have a favorite one, please forward the URL, a brief description and any comments you want to make about using it with topic maps.