How to query NUMBER OF DAYS WHERE ITEMS WERE OUT OF STOCK ?

Hello SAP "gurus",

I would like to write a query that would calculate the number of days (count) where Items where Out of Stock during the past 12 months. I guess I have to use the OINM table but I am not sure how to design the query.

To be more specific I would like to calculate the number of days (count) where the stock level of items was below the customers committed sales orders for those same days. To say it differently, I would like to have the number of days where we could not deliver all the sales orders because of lack of stock (during the past 12 months).

Thanks in advance for your help & support,

Olivier