Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	20.502666455462272
1981	22.238385734396996
1982	23.020021261516654
1983	26.971675876193054
1984	29.209267100416536
1985	31.750270201538562
1986	31.64594788429357
1987	33.93314836834456
1988	34.02981303688732
1989	33.52061273980168
1990	44.80073835668307
1991	49.39949431099874
1992	52.557029642278565
1993	59.28948029123776
1994	61.34390718805777
1995	58.95192307692307
1996	58.708741385564025
1997	56.45752036694736
1998	50.93542546771273
1999	61.874589386086576
2000	53.742497728523354
2001	65.97824259744002
2002	67.221661621258
2003	71.54218715526932
2004	73.9444614458188
2005	74.30858404637041
2006	74.35077594946581
2007	74.48073588057125
2008	72.85943223443223
2009	74.36618705035971
2010	76.47619826153301
2011	79.69327725753783
2012	75.95973953397964
2013	73.49479321630467
2014	71.66204431736955
2015	70.72871846442132