Year	% of total
1970	4.56759933188708
1971	4.376072468947649
1972	4.529840858164132
1973	4.565947543934144
1974	4.510170345744681
1975	5.6787723493541
1976	5.908420191647359
1977	6.087717577996048
1978	6.265800141717547
1979	6.431546962963433
1980	6.539553630973703
1981	6.760128764605826
1982	6.711877764865483
1983	6.422591406655159
1984	6.409493713825213
1985	6.264611026481309
1986	6.258009544006844
1987	6.204445113494131
1988	6.426575053214534
1989	6.7756624131983205
1990	3.4246575342465753
1991	3.6363636363636362
1992	3.9020657995409334
1993	3.627760252365931
1994	2.9093931837073983
1995	2.611625947767481
1996	2.773109243697479
1997	2.682313495389774
1998	2.7848101265822782
1999	2.5445292620865136
2000	2.663230240549828
2001	7.585644371941272
2002	1.7873100983020553
2003	1.6622922134733158
2004	1.7167381974248928
2005	1.7500000000000002
2006	1.7656500802568218
2007	1.7857142857142856
2008	1.794071762870515