Year	Percent
1971	4.74338
1972	4.60242
1973	4.92183
1974	5.01669
1975	5.54791
1976	5.44739
1977	6.3546
1978	6.35499
1979	6.86347
1980	6.7223
1981	7.2905
1982	7.52299
1983	8.20574
1984	9.47733
1985	10.10116
1987	11.58627
1988	12.41935
1989	12.17051
1990	14.2316
1991	15.12521
1992	21.70019
1993	19.46671
1994	20.4941
1995	15.28254
1996	18.03737
1999	19.20854
2000	20.87019
2001	21.61344
2002	22.83926
2003	24.79712
2004	26.16309
2005	27.46569
2006	28.87025
2007	30.68523
2008	34.31217
2009	40.44662
2010	44.11442
2012	56.03268
2013	62.51241
2014	62.71222
2015	63.5569
2016	64.0678