Where did you find the data source for the USA?

It'd be amazing to see this data mapped across time, as it'd be a relatively good indicator of grocery inflation.

I would be also interested in the data source. I work in european food retail business and I am not aware of any data sources like this.

Would be great for Australia, we have a supermarket monopoly, divided by two major chains, then Aldi's supermarkets and Foodland's supermarkets.