I've tried this with a few queries - civil war casualties, population london, libraries, and I was pretty pleased with the results. Zanran pulled data from tables in PDF format, tables on webpages and spreadsheets. There was a really useful 'hover over' function that brought up the exact data very quickly and I could zip down a list of results easily and smoothly. The SERPS provide title, summary based on position of search terms, date and source. Search could be limited to region, date, filetype (6 types) and specific site.
If you need figures and statistics, I would certainly suggest taking a look at this engine. There is of course room for improvement, and it can get confused when tables are used Let me know what you think of it in the comments!