Measuring concentration is necessary to analyze the market structure in an indus­try and, thus, to identify relevant elements in this structure, such as competi­tiveness and barriers to entrance, among others. These elements interfere in the conduct and performance of these firms, as well as in the structuring of the mar­ket itself. In order to address the problem of this research, we analyzed the data using two methods that demonstrate the concentration level of companies in their markets: the partial concentration rate (CR) and the Hirschman-Herfindahl Index (HHI).