Year	Percent
1981	0.28287
1982	0.99531
1983	1.46478
1984	2.02253
1985	6.41665
1986	12.65986
1987	18.14011
1988	26.04095
1989	28.09545
1990	29.71366
1991	37.79463
1992	40.09368
1993	45.75758
1994	41.70538
1995	39.79109
1996	40.19436
1997	35.7562
1998	53.34217
1999	55.27144
2000	48.23185
2001	57.27799
2002	72.97632
2003	81.1575
2004	87.56548
2005	81.33306
2006	80.64566
2007	67.89386
2008	56.60944
2009	64.78814
2010	62.41304
2011	62.80257
2012	86.20743
2013	95.71631
2014	100.67252
2015	107.33285
2016	113.8044