Accession to the European Union was the reason for the majority of referendums in countries where they are infrequent.  It was the subject of the only referendums held in the Czech Republic and Estonia and the two referendums in Norway (to be more accurate, in 1972 it concerned accession to the European Communities). One of the two to four referendums held in Austria, Hungary, Poland and Latvia, also concerned accession to the Union.