Inventory v Sales Based on Last 12 Months Sales

Hi,

I'm interested in a standard report similar to the inventory cover reports which shows the number of weeks cover but based on the last 12 months sales in order to account for seasonality.  Although obviously I could replicate this I would have thought that this would be useful to many users as I would like our team to look at the BI tool and not an excel static tool. Perhaps if this were a calculated field which could be selected then it could be chosen by users in multiple reports.