TreeMap - Allow absolute colour values

[Trevor Hills]

Currently, the colours used at each level of the TreeMap are set relative to each other, but it would useful if an absolute colour scale (with a range) could be set. 

For instance, say our colour scale is red to green. We want to show the percentage completion of projects from 0 to 100 percent. 2 projects are 100% complete but a third is 95% complete. We want these all to be mostly green, but in fact the third is shown as red because it is relativity much lower than the other two. We want to set the range of colour values here to 0 to 100 and for the colours to be set depending on where they are in this range.

Is there some way to achieve with the current TreeMap (or even some other Google chart type)? If not, could this be added as an enhancement?