I use an Excel spreadsheet as well, although a rather dated version, Excel 2000, but it does what I need it to do. At some point I had enough of paying for newer versions. Here are a couple of links to a publicly accessible version on my Windows Live Account SkyDrive. I'm fairly certain any newer version of Excel will be able to import/convert the document. The online version hasn't been updated for some time, but the formulas etc. on the various worksheets should be more or less valid & workable.
Not sure if you need a Hotmail or Windows Live account to download or view, if so & you can't, shoot a pm & I'll see about emailing a copy, my latest local version.
https://profile.live.com/cid-a0157e1...64909474%21823
If the above link doesn't fly, try this.
https://profile.live.com/cid-a0157e1...6&sc=documents