date region value%
2021-04-01 East 45
2021-04-01 West 55
2021-04-01 North 65
2021-04-01 South 75
I want to add rows below the table, as shown below without manually entering it
2021-05-01 East null
2021-05-01 West null
2021-05-01 North null
2021-05-01 South null
2021-06-01 East null
2021-06-01 West null
2021-06-01 North null
2021-06-01 South null
I need to do this because a quarter is of 3 months and we consider only first day and first month of a quarter.
Any help is much appreciated