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. Author manuscript; available in PMC: 2013 Dec 7.
Published in final edited form as: Twin Res Hum Genet. 2009 Oct;12(5):10.1375/twin.12.5.441. doi: 10.1375/twin.12.5.441

TABLE 1.

Births per year in Tasmania during selected years of interest (Australian Bureau of Statistics)

Year Total number of recorded births Estimated number of twin pairs φ Number of complete twin pairs recruited
1961 8982 157 13
1988 6779 119 75
1989 6813 119 56
1990 7043 123 52
1991 6870 120 82
1992 6987 122 34
φ

Calculations assume a twin birth rate of 3.5% of all live births (Australian Twin Registry)