Cumulative sum of 12 mobile months

[echildm]

Esteemed, I am trying to calculate by script the accumulated Consumer Price Index, this is 12 moving months, For example, for August 2023 it is necessary adds from August to December 2022 plus from January to July 2023, this indicator is monthly. I am looking for a function that adds 12 mobile months as mentioned in the example.

The data looks like this:

Where the CPI value is on the first day of each month.

Thanks in advance.