The number of Muslims in Norway was first registered in official statistics in 1980, when it was given as 1006. These statistics are based on membership of a registered , and it is most likely that the low number is due to the fact that few Muslims were members of a mosque. Historian of religion Kari Vogt estimates that 10% of Norwegian Muslims were members of a mosque in 1980, a proportion which had increased to 70% by 1998. Being a member of a mosque was an alien concept to many immigrants from Muslim countries. In Norway, because government grants to religious congregations are based on the number of registered members, except for the state church. The number of registered members of mosques increased to 80,838 in 2004, but have since dropped to 72,023 in 2006. Part of the reason for the drop could be a new methodology in the compilation of statistics.