At least for this US reader, you have your traffic light upside down.

;-)

But, more seriously, you could make your life easier if you used Red-Greeen-Blue for your range. Red-Yellow-Green just doesn't work even for your range of 10 possibilities; never mind for 100 (and certainly not for 100 distinguishable, web-safe colors.

You may find some useful ideas (albeit, neither modules nor even code snippets) at this academic (UIUC) site. In addition, Wikipedia has an interesting item on color theory, including this which is particularly relevant to your question, identifying as a "problem"...

... the tendency to describe color effects holistically or categorically, for example as a contrast between "yellow" and "blue" conceived as generic colors, when most color effects are due to contrasts on three relative attributes that define all colors:

1. lightness (light vs. dark, or white vs. black),
2. saturation (intense vs. dull), and
3. hue (e.g., red, orange, yellow, green, blue or purple).

Thus, the visual impact of "yellow" vs. "blue" hues in visual design depends on the relative lightness and intensity of the hues.

Update: Fixed the (badly borked) markup.