Super Bowl ratings have declined for their ninth consecutive year in the key demographic of 18- to 49-year-olds, hitting the lowest number since at least 1992. This year’s Super Bowl 55 experienced a 37 percent decline in the crucial young adult demographic viewership, reported Sports Media Watch. Four years ago, the game lost 43 percent in the same demographic, and in 2008, the loss was 51 percent. Sports Media Watch posted a chart showing the yearly decrease. This year, viewers aged 18-49 made up 37 percent of the audience (about 34 million.) In 2008, the same demographic constituted 51 percent of the audience. It is possible that increased online streaming, some of it illegal, may be partially responsible for the decline, but the specific data is not known. According to the sports outlet it’s estimated at 5.7 million per minute. The NFL is not the only major sports league that has …