Automatically update pivot table/chart to show only the last 6 periods

Hi all,

I'm using several Pivot Charts (in the analysis sheets) and I'd like these charts to automatically show data for only the last 6 periods (years/quarters). I've been trying to figure out how to get this to work, but no luck.

I think a macro is needed to get this to work, but I'm a real beginner with this. I would greatly appreciate any help at all! I've attached the file in case that helps.

Best,
Robert