Year	Percent
1971	43.36115
1972	46.47183
1973	52.19091
1974	53.1146
1976	51.91039
1977	53.11227
1981	46.13845
1982	49.3034
1983	50.2231
1984	47.73904
1987	60.69747
1988	64.12906
1989	61.92595
1991	65.57616
1992	66.87229
1993	69.91092
1995	71.93163
1996	78.34943
1998	81.83525
2000	93.44342
2001	90.45287
2002	88.86672
2003	88.13974
2005	88.91308
2006	89.05947
2007	92.27511
2008	94.00428
2009	96.72874
2010	100.56291
2011	103.80912
2012	103.79771
2013	102.10518
2014	100.20119
2015	97.69334
2016	94.03656