Year	Percent
1988	21.5277
1989	30.65494
1990	31.88734
1991	37.82844
1992	41.85671
1993	45.72889
1994	44.84745
1995	44.85063
1996	33.43495
1997	27.1999
1998	21.85085
1999	21.64398
2000	22.1652
2001	24.68614
2002	24.43076
2003	28.65788
2004	32.78844
2005	29.33353
2006	32.83584
2007	34.77117
2008	39.5484
2009	32.87387
2010	37.96734
2011	45.85297
2012	42.01066
2013	37.48851
2014	34.46919
2015	34.45593
2016	30.45083
2017	27.75595