how to display last 12 cumulative months from a time series

[felcar2013]

Hi

I am getting stucked here, I want to display the last 12 months from the selected month, The selected month is in this case Aug 2016. I Need to Display the cumulated values as shown in the figure, i.e., not taking Sep 2015 as the first month to start the cumulation, but using always Jan 2015 as first month of the cumulation.

Any ideas on how to show the Chart in this form, without loosing the cumulative values ?

thanks

PD: $(vL.ToMonth) = max(%date_monthyear__id)

$(vL.FromMonth) = $(vL.FromMonth) -12

the Formula Looks like this:

=sum({$<date_year=,date_monthyear=,date_month=, %date_monthyear__id={">=$(=min({1}%date_monthyear__id))<=$(vL.FromMonth)"} >}registrations_sum)
+
rangesum(Above( sum({$<date_year=,date_monthyear=,date_month=, %date_monthyear__id={">$(vL.FromMonth)<=$(vL.ToMonth)"} >}registrations_sum) ,0,Rowno())) 

[vinieme12]

Accumulative Sums

Also search the community for Rolling Total, there is lot of content available

[felcar2013]

thanks