rate	year
1.218	1950
1.552	1951
1.766	1952
1.931	1953
0.953	1954
1.753	1955
2.658	1956
3.267	1957
1.839	1958
3.405	1959
2.928	1960
2.378	1961
2.778	1962
3.157	1963
3.549	1964
3.954	1965
4.881	1966
4.321	1967
5.339	1968
6.677	1969
6.458	1970
4.348	1971
4.071	1972
7.041	1973
7.886	1974
5.838	1975
4.989	1976
5.265	1977
7.221	1978
10.041	1979
11.506	1980