Calc % change by periods
 

Is there a way to incorporate a calcualted field in a pivot table report that
will find the % change in, say, sales or units from period to period? My
pivot looks like this:
sales units
2003 2004 2005 2003 2004 2005

I would like to add an additional sales and units metric for the period
2003-2004 and 2004-2005 for each. I am not sure if I have to create a
Calculate Item for each period I would like to find. Any help would be
greatly appreciated