25.5 point rating on TV Publica and a 14 point point TYC Sports. It was shown on both networks at the same time so that's about a 40 point rating put together. Each point represents a single percentage of households with TVs I believe. Don't know how that translates to # of viewers.
http://elsolonline.com/noticias/view/147782/la-pelea-entre-maravilla-martinez-y-chavez-jr-tuvo-excelente-rating
I think that's about 13 million.
According to Wikipedia 78% of the households have television. 78% of the population is 32 million. 40% of 32 million is 13 million.