Year	Percent
1987	31.52664
1988	33.48427
1989	36.30204
1990	34.63787
1991	26.53889
1992	29.6292
1993	31.78037
1994	33.17031
1995	34.66291
1996	37.12426
1997	36.54801
1998	36.4
1999	36.50466
2000	37.19066
2001	38.21568
2002	38.43485
2003	37.45146
2004	37.18212
2005	43.68606
2006	37.95852
2007	39.75913
2008	41.35407
2009	41.36578
2010	42.52304
2011	43.51203
2012	43.83162
2013	43.84688
2014	43.30611
2015	43.11136
2016	45.35724
2017	42.46826