I have a table like this: I'd like to calculate the LiveP_SFInt for the next 8 quarters for each quarter. I.e. for 2015 -Q1 it should sum up the SFInt column through 2015 - Q2 until 2017-Q2 (8 quarters). Any idea how to do this?
| Year | Quarter | LiveP_SFInt |
| 2016 | Qtr 2 | 59000 |
| 2016 | Qtr 3 | 28832 |
| 2016 | Qtr 4 | 76694 |
| 2015 | Qtr 1 | |
| 2015 | Qtr 2 | |
| 2015 | Qtr 3 | |
| 2015 | Qtr 4 | 99000 |
| 2014 | Qtr 1 | |
| 2014 | Qtr 2 | |
| 2014 | Qtr 3 | |
| 2014 | Qtr 4 | 405000 |
| 2013 | Qtr 1 | |
| 2013 | Qtr 2 | |
| 2013 | Qtr 3 | |
| 2013 | Qtr 4 | 202529 |
| 2012 | Qtr 1 | 227467 |
| 2012 | Qtr 2 | 59913 |
| 2012 | Qtr 3 | |
| 2012 | Qtr 4 | 122440 |