Year	Percent
1991	32.41823
1992	31.72889
1993	31.56571
1994	30.81093
1995	30.09298
1996	29.26119
1997	28.2839
1998	27.36965
1999	25.76353
2000	24.66334
2001	23.3803
2002	22.17942
2003	21.73591
2004	21.43038
2005	21.66666
2006	22.01461
2007	21.33077
2008	20.84443
2009	20.42465
2010	20.09705
2011	19.4542
2012	18.97466
2013	18.08919
2014	17.48014
2015	16.96879
2016	16.73266
2017	16.31716
2018	15.89504
2019	15.43963