The Overture Keyword Selector Tool, located at http://inventory.overture.com. Hasn't been returning updated results for quite a while now. Since January 2007 to be exact. And all tools that query the same database is also outdated. You wouldn't be doing yourself any favors if you base your marketing campaign on old stats that the tool now provides. Some alternatives are:
Keyword Discovery and Wordtracker provides more detailed reports if you subscribe to their services.