Year	% of total
1971	29.75
1972	31.517241379310345
1973	26.427962489343564
1974	30.972762645914397
1975	19.96438904963276
1976	14.71654895972514
1977	43.33752357008171
1978	49.73835354179962
1979	48.03747534516765
1980	72.55556531670034
1981	83.465877566118
1982	83.78951990632318
1983	90.7754093296262
1984	91.10437329770286
1985	89.39112191865732
1986	89.63521335307578
1987	80.00888494002666
1988	68.65671641791045
1989	66.40821458507963
1990	73.49166666666666
1991	79.78856319077366
1992	80.18577075098814
1993	79.29657794676807
1994	76.48928571428571
1995	77.83343980096157
1996	77.61059884824074
1997	78.98414581891295
1998	79.97091614154145
1999	78.94053163514242
2000	79.32288401253919
2001	81.82381941645221
2002	85.23166878303753
2003	88.01340860973889
2004	92.5901842390463
2005	28.421052631578945
2006	14.599532862253495
2007	16.87877967325571
2008	14.075037952721752
2009	8.328269083414803
2010	34.64463891387912
2011	37.79938036843961
2012	43.30913990177756
2013	40.72780801752764
2014	35.57283673710306
2015	25.73198688372363