Year	% of total
1971	99.22764759785312
1972	99.42203349846662
1973	100
1974	100
1975	100
1976	100
1977	100
1978	100
1979	100
1980	100
1981	99.98458811743855
1982	81.84150722087824
1983	67.1264367816092
1984	50.01022843504944
1985	45.57413167444271
1986	44.46176874142447
1987	48.59421847598575
1988	53.23997519636213
1989	52.34928861291742
1990	49.89472676811178
1991	46.611508784977225
1992	41.687877823735285
1993	37.75514126465501
1994	39.31536729524346
1995	37.3442892358258
1996	30.570840121730043
1997	28.723646723646723
1998	29.803714925569754
1999	32.599770495983684
2000	31.09397341834462
2001	24.74573957361607
2002	22.446153846153845
2003	22.869411789715354
2004	13.299773683876563
2005	13.690794617505453
2006	11.102100557775229
2007	10.776695419393219
2008	10.508403213922318
2009	4.0485020360674815
2010	3.660971821610828
2011	7.304076810938522
2012	20.940272685427676
2013	3.6610025765630603
2014	0.4916711887260948
2015	0.6523837698128484