Year	Percent
1980	47.50377
1981	39.35154
1982	43.55364
1983	49.7242
1984	39.65062
1985	52.93303
1986	55.29099
1987	51.9847
1988	52.92475
1989	59.78114
1990	51.73346
1991	67.37231
1992	69.51577
1993	76.33806
1994	70.29569
1995	90.70944
1996	104.6949
1997	125.11035
1998	142.17561
1999	152.96514
2000	146.89427
2001	131.65033
2002	100.70067
2003	123.93949
2004	132.98429
2005	129.83978
2006	141.23218
2007	137.60728
2008	78.74589
2009	104.5673
2010	115.49734
2011	100.79122
2012	115.55579
2013	143.99442
2014	151.08549
2015	138.33638
2016	146.86159
2017	165.65086