The I. liga started as a competition for 12 teams, each playing all other teams twice.
In 2002, the number of teams was reduced to ten and after the regular season was followed with a playoff with eight best teams. In 2006, the system was abandoned and a league of 12 teams was re-instated.
Since 2009-10, only eight teams participated in the league and after the regular season, a playoff system was held. In those two playoff groups, place 1 to 4 for the championship and the relegation group for teams placed between 5th and 8th positions. In 2010–11 nine teams played again only a double-round robin.