Calculating Rolling Sum based on quarters & years

Hi guys,

I am trying to make a rolling sum calculation based on quarters and years - for example I want to calculate automatically the 2018 Q1 rolling as a Q2 2017 + Q3 2017 + Q4 2017 + Q1 2018 (3 previous quarters plus the current one) vs the same for the last year (2017 Q1 rolling) in a relatively big database that has data points as per below (three columns --> One for the year, one for the quarter and one for the values.

I would like to insert a formula that calculates the rolling quarters automatically for the entire dataset (which is sorted by year and quarter).

Could anybody help me on this?

Many thanks in advance!!

Stathis

2014 Q1 38296.32305
2014 Q2 36256.39538
2014 Q3 236454.7516
2014 Q4 176535.5231
2015 Q1 330038.5454
2015 Q2 122090.511
2015 Q3 62256.79726
2015 Q4 24985.23098
2016 Q1 171957.0598
2016 Q2 45976.90839
2016 Q3 109547.2096
2016 Q4 49663.2218
2017 Q1 121398.9867
2017 Q2 67666.01569
2017 Q3 87793.55059
2017 Q4 97230.40709
2018 Q1 46852.26083

If you have dates for beginning of each quarter for each year e.g for 2014, Q1 is 01/01/2014, Q2 is 01/04/2014 etc then it will be easier to create a formula.

Unfortunately I have no dates for it just the quarter and the corresponding year