I've thought of another way. Right click the knob and select create automation clip as usual. When the clip appears, double click on its title bar, and a settings window with min and max knobs will appear.
If you set the min knob to 31%, for example, 0% in the automation clip will correspond to a 31% value for the automated knob. Similarly, if the max knob is at 76%, 100% in the clip corresponds to a 76% value for the automated knob.
Set the min and max values to your preferred min and max values, then set up the automation clip so that it starts at 0% and ends at 100%.