RANK&CALCULATE SOS!

Hey,
, everything I've tried so far does not work :(
I have a table that contains the customer calls to the call center. 
Each customer has an institutions ID so you can see from which institute he is contacting us.
I need to count the number of calls for each institute in 2016 and then rank the institute, 
so that only the 120 institutions with the most calls to the call center will be shown.
The next step, is to present the amount of calls in 2017 of the same 120 institutions (i need to compare 2 years) 
The next step is to calculate the target-
X = the number of calls of 120 institutions with the most calls for 2016
Y = the number of calls of the same 120 institutions in 2017
(X-(X*0.2))/Y
I managed to produce all of these in the table,
but I need to present a KPI visual which will show me only the calulation

I've been dealing with it for over a week and I can not find a solution. Really needs help!