Year	Percent
1961	16.10247
1962	16.20926
1963	17.41071
1964	18.30521
1965	18.02799
1966	16.78602
1967	17.36815
1968	18.85964
1969	18.91508
1970	18.47675
1971	21.36996
1972	31.20905
1973	44.87811
1974	46.88449
1975	39.97879
1976	41.77373
1977	44.97497
1978	41.93643
1979	45.47961
1980	43.18248
1981	38.24054
1982	36.83398
1983	36.19603
1984	39.44282
1985	42.1146
1986	43.57967
1987	43.16645
1988	43.251
1989	40.64747
1990	40.6248
1991	42.26481
1992	47.84987
1993	52.64326
1994	53.53461
1995	61.03899
1996	59.40451
1997	49.15752
1998	54.04149
1999	63.11836
2000	66.17836
2001	65.32997
2002	60.91581
2003	69.41797
2004	72.16405