Changing index benchmark

[joust41]

Hi!

I've got a time series data set of stock prices between 1990-01-1 and 2015-01-1. This is indexed data, with 2010-01-01 equal to 100 and everything else scale accordingly. However, I need the data to be scaled so that the first period, 1990-01-01 is equal to 100. The issue is that I don't have the actual values, only the index with the 2010-01-01 value = 100. I haven't managed to find the actual values. Is there any way/formula in excel to scale the data in the way I require?

Data was taken from the official OECD database:
http://stats.oecd.org/index.aspx?queryid=84#

[CK76]

Issue is that quite a few countries are missing data for 1990.

At any rate, since all values are based on 2010-01-01 = 100. You can calculate value for each month using following calculation.
=100*(Given month's index value/1990-01-01 index value).

Taking Australia for example, 2010-01-01 calculated index value based on 1990-01-01 being 100.
=100*(100/36.2) ≈ 276.2431

[joust41]

This was very helpful, thank you.