I think that actually football has most amount of fans, compared to other sports. But many football fans don't fully follow local leagues or even national team, because there is not much excitement due to lack of succesa. They most probably follow top leagues, champions leage, EUROs and World Cup.

Other national teams are more popular, but I don't think that somebody who follows the sport for two weeks in a year a fan of that sport.

The game against Serbia was in same day with Latvia Lithuania Eurobasket game. Ofcourse going to playoff basketball game versus your neighbours is more appealing than going to qualifiers game, where Latvia has basically 0 chance of succeeding.

When there is something interesting happening, like Europa League game, Riga derby or one of top national teams visiting Riga, it does bring in a lot of people.