Year	% of total
1970	84.81345437093219
1971	84.99729071685283
1972	84.82806254621144
1973	84.51762388905846
1974	84.32674563602451
1975	84.1495403161724
1976	83.58491391352493
1977	83.10673956173986
1978	82.84307189838238
1979	82.71382051230043
1980	82.33057215247156
1981	81.94152977615956
1982	81.65416210912085
1983	81.43966042174814
1984	81.22212926031843
1985	80.94191411512277
1986	80.56605161321531
1987	80.42360227949065
1988	78.86020739279525
1989	78.37462272462184
1990	80.28870084619214
1991	80.4679552390641
1992	79.375
1993	79.80884109916367
1994	79.47269303201506
1995	78.57142857142857
1996	75.35353535353535
1997	73.95762132604237
1998	73.28296703296702
1999	72.36111111111111
2000	69.79241231209735
2001	69.26438455935907
2002	68.14486326681448
2003	66.22613803230544
2004	62.58890469416786
2005	63.95939086294417
2006	62.40282685512367
2007	60.302197802197796
2008	56.78131083711876