TreeMap Color Saturation Data Label please

Please add a data label for the color saturation in a TreeMap. At present the data label only indicates the rectangle size and NOT the second 'color sat' dimension. While color saturation is excellent visually to illustrate a second dimension (eg stock market returns), data visualisation theory shows people have difficulty if asked to numerically value what a color saturation level means.. ie is one color level double the other etc. For example, people can accurately assess bars on a bar chart for relative proportion. That is why is actually very necessary to have a data label option for the color saturation to use when required