When the methodology of a social index changes



How can I use an index that has gone through a methodology change?

I have obtained an index for my dependent variable (ethical behavior of firms).
The time span is from 2005 to 2015.

The methodology to measure sub-indicators has changed.
Past: three sub-indicators (A: 7, B: 10, C: 8) = 25 points (maximum score)
Now: three sub-indicators (A:10, B:15, C: 10) = 35 points (maximum score)
The evaluators added several new items to each of those three sub-indicators so the total score increased.

What kind of solutions do we use in this situation? Please help : (