I have a formula in C19 that calulates a percentage. Everything works fine.
What I want to do is have the color of the cell change when a certain
threshold is met. Under CF I created the following set of rules :

=$C$19=0 format green
=$C$190 format blue
=$C$19<0 format red

Seems to work except the same rules get appended over and over again every
time C19's percentage changes. If C19 changes 9 times I end up with 6
additional rules (original 3 plus 6 additional - total 9). Not good as C19
can change dozens of times in a month. Any guidance ?