Year	Percent
1975	14.9362
1976	14.81054
1977	20.45099
1978	13.97476
1979	18.37208
1980	21.02889
1981	26.96558
1982	30.48343
1983	33.77419
1984	34.79545
1985	38.66533
1986	35.60632
1987	39.76611
1988	38.9906
1989	36.64008
1990	35.41213
1991	32.61405
1992	31.1387
1993	17.06061
1994	20.56434
1995	25.26389
1996	22.39031
1997	15.56237
1998	14.85275
1999	15.82524
2000	21.0197
2001	15.87806
2002	16.35358
2003	15.8395
2004	8.28179
2005	9.98423
2006	7.12819
2007	6.32384
2008	4.8801
2009	5.13621
2010	4.40062
2011	4.31941
2012	5.25669
2013	5.91113
2014	11.06749
2015	8.79166
2016	10.61954