Year	Percent
1988	95.54736
1989	100.14722
1990	106.50046
1991	96.28221
1992	85.86489
1993	69.97768
1994	66.70398
1995	69.06853
1996	62.78206
1997	51.46691
1998	44.83052
1999	39.58356
2000	40.23669
2001	48.00634
2002	40.71587
2003	45.45156
2004	56.34872
2005	56.23002
2006	57.17012
2007	64.38917
2008	72.56217
2009	58.51941
2010	61.1172
2011	65.91031
2012	62.82403
2013	59.09843
2014	55.07098
2015	46.66158
2016	47.46809
2017	46.55301