Year	Percent
1981	28.12808
1982	43.34285
1983	54.4795
1984	59.79383
1985	71.01948
1986	60.27937
1987	55.11548
1988	46.91413
1989	46.56653
1990	43.26333
1991	41.81678
1992	39.61419
1993	30.03253
1994	43.30529
1995	44.18642
1996	40.72466
1997	42.4069
1998	47.78567
1999	56.29992
2000	60.8756
2001	62.05806
2002	63.98343
2003	55.21399
2004	51.22691
2005	50.88669
2006	49.31437
2007	39.16136
2008	35.93891
2009	43.55536
2010	56.08683
2011	57.96819
2012	74.24424
2013	83.29664
2014	87.3347
2015	101.58583
2016	100.27563