Year	% of total
1970	9.987722587703304
1971	9.722789815180818
1972	9.768588493440902
1973	9.239001158269957
1974	9.697633692695966
1975	9.20601015548699
1976	9.186790851522673
1977	9.209523466939268
1978	9.708601583722226
1979	9.803555473737974
1980	11.253446734612538
1981	12.734470844683726
1982	13.237557334812692
1983	13.52037290798012
1984	14.551318097126732
1985	14.220773217599145
1986	13.487058448846467
1987	14.178715634383554
1988	13.983546850043515
1989	15.536317139473818
1990	13.445378151260504
1991	14.166666666666666
1992	13.934426229508196
1993	14.754098360655737
1994	15.384615384615385
1995	14.754098360655737
1996	14.87603305785124
1997	14.754098360655737
1998	13.953488372093023
1999	13.636363636363635
2000	13.533834586466165
2001	14.074074074074074
2002	14.814814814814813
2003	15.217391304347828
2004	15.492957746478872
2005	15.862068965517242
2006	15.333333333333332
2007	15.2317880794702
2008	14.64968152866242