"By the way, In case you read this, I was wonding why use INDEX,MATCH
and not
Vlookup?"

A VLOOKUP looks to the left most column to pick up what you are trying
to match. So in your example IF the data was :

Jan 0.124
Feb 1.150
Mar 0.456

You could use a VLOOKUP, but in your example you have the data to the
left of what you are trying to match and therefore you can not use a
VLOOKUP.

Chad