l Canadian anencephaly data from Elwood (1975)zBz{BT20 Jan 2000 12:05lbibirthsmonthccases%12.0g%8.0gCY%8.0gCYNumber of Birthsx _  # zBV^z{B Month of Birthsx _  # zBV^z{B Number of Casesx _  # zBV^z{B =3oj }vxJx _  #