How to make my own formula for OLAP Pivot table?
 

Hi,
How can i create my own formula in a PivotTable or PivotChart report
that depends on an OLAP data source. This option is available for
pivottables from other data sources as 'Calculated Item' and
'Calculated Field', not available for pivot table OLAP data source.
I need to evaluate a year-to-year growth rate for a year seris include
12 years, my function is [(X2/X1) -1] *100
where X2 is the value of current year,
X1 is the value of previous one.
Any sugessions will be appreciated.
Thanks in advance.