We don't have a monopoly in the oil business. An oil company that controlled all the production and sales is a monopoly, like Standard Oil in the US in the late 19th Century. A national oil company like Pemex in Mexico is a monopoly. Whoever wrote that headline needs to learn how to use a dictionary.
Bob Ebersole

By definition you need complete control of all sales to be called a monopoly, but I think it is obvious that the effects of monopolistic practice become visible long before the 100% mark.