property CategoryAxis.Angle as String
Specifies the rotation angle (in degrees) for the title and labels of the axis, in 'title,label' format

TypeDescription
String A string expression that defines the rotation angle for title and labels of the category-axis, in 'title,label' format 
By default, the Angle property is "". The Angle property specifies the rotation angle (in degrees) for the title and labels of the axis, in 'title,label' format. Currently, only orthogonal angles are allowed.

For instance: