Year	Percent
1964-01-01	2.617840
1965-01-01	2.875693
1966-01-01	3.140063
1967-01-01	3.512913
1968-01-01	4.158174
1969-01-01	4.590092
1970-01-01	5.147444
1971-01-01	5.836279
1972-01-01	6.432466
1973-01-01	5.728966
1974-01-01	5.205809
1975-01-01	5.893284
1976-01-01	5.350648
1977-01-01	5.095603
1978-01-01	5.051163
1979-01-01	4.742763
1980-01-01	4.883180
1981-01-01	5.182199
1982-01-01	5.631636
1983-01-01	5.788091
1984-01-01	5.942959
1985-01-01	7.800511
1986-01-01	11.243610
1987-01-01	13.691820
1988-01-01	14.410810
1989-01-01	13.454980
1990-01-01	13.666930
1991-01-01	17.432650
1992-01-01	18.167280
1993-01-01	17.050800
1994-01-01	21.380560