TickLabelSpacing Property
Returns or sets the number of categories or series between tick-mark labels. Applies only to category and series axes. Read/write Long.
Remarks
Tick-mark label spacing on the value axis is always calculated by Microsoft Excel.
Example
This example sets the number of categories between tick-mark labels on the category axis in Chart1.
Charts("Chart1").Axes(xlCategory).TickLabelSpacing = 10