No major nation is gripped annually by a sporting event as much as the US is by Super Bowl on the first Sunday of every February, when two teams compete for the National Football League (NFL) championship. The exception is the FIFA World Cup Final, but only for the two nations whose teams are involved and that happens every four years. Then the summer Olympics attracts the highest overall audience, but that is aggregated across large numbers of individual events. As it happens, Super Bowl audiences have been subsiding over the last four years having peaked at 114.4 million in 2015 and fell back a further 7% for the 2018 final to 103.4 million, according to Nielsen, with signs it may…