Year	Percent
1970	18.04849
1971	17.5372
1972	18.42471
1973	9.33721
1974	17.62402
1975	8.5575
1976	10.45957
1977	11.02004
1978	12.37629
1979	13.15241
1980	18.6296
1981	13.47374
1982	12.51422
1983	21.35705
1984	10.77866
1985	15.21044
1986	46.80639
1987	48.02632
1988	63.56122
1989	88.62031
1990	79.51445
1991	57.40417
1992	69.67653
1993	57.54605
1994	62.71717
1995	66.31307
1996	63.28582
1997	40.3791
1998	27.38786
1999	33.42271
2000	27.96419
2001	58.18879
2002	46.60321
2003	71.30922
2004	73.07878
2005	39.88551
2006	50.86167
2007	22.02202
2008	20.12989
2009	20.78588
2010	16.76535
2011	11.4979
2012	13.82431
2013	12.04485
2014	9.71939
2015	11.82319
2016	9.74534
2017	11.38829
2018	8.78391
2019	8.71314
2020	5.8576
2021	7.44876