I have tried to reproduce the problem you mentioned.
My guess is that, Excel has interpreted the YEAR column (say column A) as part of the data, because Excel will try to interprete any number-like value as number.
Here is a simple trick that solve the problem.
- Change the value in YEAR column (ie. 1999, 2000, 2001, ...) to any text (ie. A, B, C, ...)
- Highlight both columns (eg. A1:B10), and press the chart button as usual.
(As Excel cannot convert A/B/C to any number, it will make the A/B/C as axis label correctly.)
- Change the text back to the YEAR (1999, 2000, ...)
Alternatively, if you cannot change any cell value, you can manually set it in the chart wizard.
- Highlight ONLY the REVENUE column (eg. B1:B10), and press the chart button.
- Set A2:A10 as axis label in the wizard, and continue with the chart wizard
(As I only have Excel 2003 at the moment, I will update the answer if there is any difference in Excel 2007.)