Sometimes it is not the total number of citizens that is used, but the number of registered voters. Azerbaijan uses the average voter representation norm by dividing the total number of registered voters by the number of seats (125). Latvia also uses the number of registered voters. Voters residing outside of Latvia are included among voters of the Riga constituency. Russia uses registered voters as a criterion for its single-member constituencies, based on the number on the date closest to the day of the adoption of the CEC decision for consideration of the State Duma (January 1^st or July 1^st). In Sweden the seats per constituency are calculated based on the relationship between the number of persons entitled to vote in each constituency and the total number of persons entitled to vote in the whole country. Ukraine also uses the number of registered voters, based on the data of the State Voter Register and determined by the Central Election Commission. In Estonia the seats per constituency are calculated based on the number of voters in civic register in the beginning of the month when elections are called. Iceland also uses the number of voters to determine the boundaries of each constituency as to ensure that each constituency has more or less the same amount of seats. Hungary uses the number of voters, which has to be approximately equal in all - one-member - constituencies.