Year	% of total
1971	0.13121924548933844
1972	0.1154068090017311
1973	0.09100561201274078
1974	0.11496895838123705
1975	0.1755669348939283
1976	0.23783636857841803
1977	0.7294429708222812
1978	0.5147342684339209
1979	0.6655873358517719
1980	1.005053029041035
1981	0.6888015928536835
1982	2.231268679789756
1983	2.6475249370746714
1984	5.113314447592068
1985	14.701748221031362
1986	12.60131591494231
1987	9.919618408267821
1988	10.522026162435306
1989	9.435732999648067
1990	7.346070573935504
1991	7.571445280517759
1992	6.923076923076923
1993	7.581173106587907
1994	4.423878441797119
1995	6.28314365727224
1996	13.219157568001744
1997	18.501394577480713
1998	22.57924864110828
1999	26.991214520177643
2000	36.79178626628395
2001	39.93411264612115
2002	33.276249819464795
2003	28.21873819418209
2004	28.940078989223867
2005	26.971555854119895
2006	26.9341176056214
2007	28.24478703594974
2008	25.894016869173477
2009	26.60809741444744
2010	34.39668152696997
2011	36.634092748930264
2012	38.7611250531397
2013	42.62349533653974
2014	42.78170381299992
2015	44.51482169075267