Lots of money, few companies

Got the following "summary" of a research report being ofered for sale. "The U.S. mineral construction materials industry includes roughly 45 companies that operate 118 cement plants, hundreds of local sand and gravel quarriers, and thousands of ready-mix concrete operators. In addition, about 130 companies operate 200 brick plants, 500 produce asphalt, 190 produce gypsum products, and about 1,000 produce concrete blocks and pipes. The combined annual revenue of the industry is about $65 billion, of which $35 billion is due to sales of cement and concrete products." Hmmmm, only 45 companies, huh? Interesting. Your comment?