Year	Percent
1965	6.44413
1966	4.83427
1967	4.98831
1968	5.688
1969	4.84659
1970	5.96487
1971	7.75341
1972	7.32954
1973	9.17845
1974	8.76015
1975	14.4952
1976	15.13165
1977	16.0243
1978	18.27995
1979	15.81814
1980	18.28616
1981	17.60721
1982	17.14857
1983	19.6327
1984	18.6621
1985	22.55613
1986	20.26416
1987	21.18878
1988	22.29215
1989	21.50691
1990	18.12582
1991	20.25347
1992	20.70466
1993	22.5709
1994	22.40355
1995	25.1995
1996	27.20509
1997	25.34072
1998	24.83937
1999	20.48352
2000	24.31487
2001	22.34302
2002	20.24621
2003	21.40938
2004	24.53115
2005	26.45116
2006	26.8519
2007	28.68525
2008	30.31565
2009	31.67438
2010	38.27121
2011	37.98723
2012	34.49707
2013	37.32136
2014	41.16781
2015	39.05747
2016	33.71321
2017	42.51107