Year	% of total
1970	70.19586849256373
1971	77.17127886186064
1972	68.99694864910975
1973	75.30036840308115
1974	76.48976326592137
1975	75.7145218871617
1976	67.28765381018358
1977	77.7679167705035
1978	70.76688527839993
1979	63.52833742567775
1980	63.540576512702096
1981	64.64366452445526
1982	64.88765474137031
1983	60.06061319289737
1984	69.59394251687223
1985	63.78601098438948
1986	62.75157813243604
1987	55.69158657446911
1988	60.9193307519668
1989	59.96252637361851
1990	77.77777777777779
1991	82.17821782178217
1992	83.17757009345794
1993	84.87394957983193
1994	83.89830508474576
1995	86.86131386861314
1996	86.13138686131386
1997	86.52482269503547
1998	85.49618320610686
1999	86.52482269503547
2000	83.33333333333334
2001	84
2002	82.45614035087719
2003	84.0909090909091
2004	82.64462809917356
2005	82.45614035087719
2006	81.08108108108108
2007	81.57894736842105
2008	82.92682926829268