In an Excel chart, how do you craft X-axis labels with whole number intervals?
Solution 1:
You can make the changes you'd like on a Value Axis, but the chart you've created doesn't use that, it uses a Category Axis. So, without changing your chart type, you can't do what you'd like, the version of Office is generally irrelevant for this issue.
You can approximate a Value Axis by using the Category Axis Date Option (as shown in your example), but you'll have to convert your data values to serial date values, then set a Min and Max (this is not a pretty option, but it is possible), and there's still no way to assign a 0 starting point, so the best you could do is still 1, 501, 1001,...
Generally, if you use a Line or Area chart, Excel makes the X Axis a Category Axis. If you create an XY (Scatter) Chart, it creates a Value Axis. John Peltier's Blog has a great discussion of the differences and even a few work-around suggestions for Filling under an XY Chart to mimic an area chart.
You'll probably find that the easiest way to get what your looking for (and keep the same chart appearance), is to do what you were trying to avoid, and include a helper data series for your label, then just include it on each chart. That will give you the most flexibility with the least effort and redundancy.