A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Paul, just re-visting this and, as far as I can see, my website item 115 seems to give you what you want.
Take the following actions:-
1. Pull up my item 115 on the screen.
2. Remove the data in cells:-
A2
A5
A8
3. Change cell B2 to read 2010.
Change cell B5 to read 2011.
Change cell B8 to read 2012.
You can change the other numbers as desired and add in months if you like.
You should now have months as the first (upper) level of the X axis and years as the second (lower) level of the X axis with a line in between Dec and Jan on this second (lower) level.
I think that the above gives you what you want.