Inventory quantity history, or how many days a product is out of stock?

In order to predict the annual demand for a product, we need to know how many days it was out of stock. If a product was out of stock half the year, and we sold 100 a year, then we can predict that annual demand should be 200.

Is there any extension that can track this? Perhaps make a backup of the products table everyday?

Related to my other thread Getting inventory quantity into Google Sheets, I’m currently thinking of using a product feed extension like Mirasvit’s, then have a script in Google Sheets that backups the product feed every day.