CREATE TABLE Products (Code NUMBER, Name VARCHAR2, Price NUMBER, Manufacturer NUMBER)
CREATE TABLE Manufacturers (Code NUMBER, Name VARCHAR2, Headquarter VARCHAR2, Founder VARCHAR2, Revenue FLOAT)

For those records from the products and each product's manufacturer, a bar chart shows the distribution of headquarter and the average of revenue , and group by attribute headquarter.
SELECT Headquarter, AVG(Revenue) FROM Products AS T1 JOIN Manufacturers AS T2 ON T1.Manufacturer = T2.Code GROUP BY Headquarter
SELECT "Headquarter", AVG("Revenue") FROM "Products" "T1" JOIN "Manufacturers" "T2" ON "T1"."Manufacturer" = "T2"."Code" GROUP BY "Headquarter"