Need Bar Animation Gradient Fixed I have searched all over the Internet and here, but no success. I am relatively new to Blender, only used it a few months so far.

The project I'm working on is a Bar Chart. In the scene the bars are cubes with their top faces Hooked to an Empty that is animated via Python.

What I need is a way to fix the gradient position across all bars. As they grow taller, they reveal more of that gradient. 

This image I made in illustrator to give you a better idea.
This is a solution based on the world position in relation to the object. You can adjust the height by changing the denominator on the math-divide node.