Index calculation

Hi all,

Could you help me find a solution for this problem? 

I am trying to calculate the index column in the yellow column in the screenshot and see attached for the example file and the calculations done so far.

https://docs.google.com/spreadsheets/d/1wg7SR9aPMlBlWlBW1tIxmBbZbKwGBqmo/edit?usp=sharing&ouid=107445963370464826577&rtpof=true&sd=true 

In row 1 in the index column you see 100. This should always be the value at the selected start date. So if start date is 10/01/2020, then we start index calculation at that date. Index = 100.  So if start date is 10/07/2020, then we start index calculation at that date. Index = 100. And the calculation goes on from there. The calculation for row 2 is as follows: =H2*(1+G3)

All comments are much appreciated ! 

Thanks,
Martin