Year	% of total
1970	80.8385287926133
1971	80.13549251666929
1972	80.5434087409358
1973	80.5325562986977
1974	80.8103264497783
1975	80.54706484586221
1976	80.05303756950177
1977	79.93365067389188
1978	79.8162460803836
1979	79.23248482115267
1980	77.58712706648073
1981	77.6587943444933
1982	76.76915385606982
1983	76.40606803679222
1984	76.24839581065491
1985	76.14914808172595
1986	75.2235519528706
1987	73.90449471586149
1988	72.79124839383783
1989	72.06005577976731
1990	64.70588235294117
1991	64.70588235294117
1992	61.53846153846154
1993	60.37735849056604
1994	59.25925925925925
1995	56.36363636363636
1996	57.14285714285714
1997	57.14285714285714
1998	56.14035087719298
1999	55.172413793103445
2000	54.385964912280706
2001	51.724137931034484
2002	50.877192982456144
2003	50.877192982456144
2004	49.122807017543856
2005	51.78571428571429
2006	49.18032786885246
2007	49.18032786885246
2008	50