How to average values along a direction in space?

Hello,
I have a 3D airfoil case which I want to calculate the average of the fields in the spanwise (z) direction and finally get a 2D plane(xy) which the averaged values are set on it.
Is this possible?

Thanks

Slice + Descriptive Statistics ?

Thank you, but Descriptive Statistics gives the average of all points on the slice.

I need the average of slices!
For example, I have 32 slices with exactly same number of points which they only differ in the value of z coordinates. I want to average all of them and finally have 1 slice which is the average of all of the slices.

This is much more specific, this is doable with either the PythonCalculator or ProgramableFilter, but not trivial.