Year	% of total
1970	82.69740614647793
1971	82.50921804292534
1972	82.66093446927363
1973	83.53422698724327
1974	83.7737770494498
1975	86.23292844415438
1976	87.23691240202803
1977	86.9875130411008
1978	84.64157561697449
1979	84.80015625459568
1980	85.66904115533262
1981	86.60365653297032
1982	89.24734424335595
1983	87.87175912551768
1984	86.57041638342125
1985	83.1680525271162
1986	82.47764965697581
1987	82.0760304747872
1988	81.27977995805479
1989	82.1767250838197
1990	79.54545454545455
1991	79.54545454545455
1992	79.12087912087912
1993	79.34782608695652
1994	78.72340425531915
1995	79.16666666666666
1996	78.49462365591397
1997	78.02197802197803
1998	77.17391304347827
1999	77.77777777777779
2000	78
2001	79.82456140350878
2002	80.17241379310344
2003	80.17241379310344
2004	78.57142857142857
2005	78.37837837837837
2006	79.16666666666666
2007	79.33884297520662
2008	78.15126050420169