Many attribute this to the double majority requirement for a referendum to be carried. There have been five instances – in 1937, twice in 1946, and once each in 1977 and 1984 – where a national "Yes" vote has been achieved but failed to win a majority of states. In three of these instances, the referendum received a majority in three states. The converse situation, where there is a majority of states but not an overall majority, has not yet occurred.