How do I change the value on the horizontal axis in a X-Y graph so that it
follows the example below?

X-axis Y-value
0.00 2
0.25 4
0.50 6
0.75 8
1.00 10
1.25 12

In the current form, the graph shows the X-axis going from {1;2;3;4;5;6;7}.
I want to change these values to {0.00; 0.25; 0.50; 0.75; 1.00; 1.25}. I use
Excel 2007. How do I do that?
etc.