Year	% of total
1971	81.53638814016172
1972	81.14558472553699
1973	82.72357723577237
1974	69.81285598047194
1975	72.79693486590038
1976	73.16239316239316
1977	73.16239316239316
1978	90.25641025641026
1979	88.09523809523809
1980	88.14814814814815
1981	88.14814814814815
1982	87.63888888888889
1983	73.81864623243933
1984	89.70149253731343
1985	86.9727047146402
1986	86.9727047146402
1987	86.54320987654322
1988	86.0122699386503
1989	86.6910866910867
1990	86.20689655172413
1991	82.65524625267666
1992	88.70116156283
1993	93.6842105263158
1994	93.717277486911
1995	93.75
1996	89.98054474708171
1997	76.35253054101221
1998	80.42488619119878
1999	66.96629213483146
2000	63.11418685121107
2001	62.08791208791209
2002	64.75920679886686
2003	62.205513784461154
2004	78.40501792114696
2005	79.64824120603015
2006	80.61101028433151
2007	77.61889959589679
2008	75.40904716073146
2009	65.34318901795143
2010	67.95742338043678
2011	70.90780392850823
2012	60.79948420373952
2013	58.02093476144109
2014	53.175105485232066
2015	53.17492830807047