Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	0
1993	0
1994	0
1995	22.77704774419623
1996	23.99470461691213
1997	22.18700475435816
1998	20.69781194559432
1999	22.905532033039496
2000	21.94114610221993
2001	22.047048600335177
2002	21.128287034396212
2003	20.355804254869874
2004	19.266236007692687
2005	27.946365561044463
2006	39.593601034176295
2007	44.000152473888846
2008	40.98932533314728
2009	39.19928884206367
2010	47.12820197800848
2011	59.80999269202661
2012	60.47556528081692
2013	58.383667871178744
2014	53.70120060427765
2015	53.70031554106012