Excel 2007 : Identical Headings-formatting as table/chart adds digit

Hi Excel Experts! This may be a dumb question answered elsewhere, but I don't think I'm asking the right questions w/correct terminology. Help!?

I have several Excel-based reports that have to be formatted as tables and charts. Before using FORMAT AS TABLE command, the data looks like this: pls note duplicate headings:

2007 2007 2007 2008 2008 2008 2009 2009 2009 2010 2010 2010
Wave 1 Wave 2 Wave 3 Wave 1 Wave 2 Wave 3 Wave 1 Wave 2 Wave 3 Wave 1 Wave 2 Wave 3
25% 50% 12% 11% 15% 5% -1% -7% -13% -19% -25% -31%


See how it's added a digit to my original entries? I've tried unticking 'my table has headers' but that led to a whole new issue, adding a nonexistant series; using ' before entries, changing to Text; etc--no dice. My goal is to have a lovely table and chart on each spreadsheet that I can share w/clients. We've recently upgraded from to 2007 from 2003 and many of our reports have identical headings like this, so any advice is beyond appreciated!!!