How to normalize indicator?

I have an indicator that has dynamic range (min changes from -100 to -30; max changes from 0 to 12-15).

How to normalize it? I want indicator to have min=0 and max=1. I tried to use WPR principle but can't complete it.

Please, help.

You could try this method:
Normalized_value = (Indicator_current_value - Min) / range,

where:
range is Max - Min (supposedly you know your Max and Min)
this should give you numbers between 0 and 1