Year	Percent
1991	38.21844
1992	38.3356
1993	38.19851
1994	36.10875
1995	35.3902
1996	35.42922
1997	35.37474
1998	35.11634
1999	34.78827
2000	33.60328
2001	32.48181
2002	31.89197
2003	31.70926
2004	31.3554
2005	29.7574
2006	28.52853
2007	28.43723
2008	26.83042
2009	25.75964
2010	24.8606
2011	24.01152
2012	23.26241
2013	23.33103
2014	22.94567
2015	22.10228
2016	20.80358
2017	19.91219
2018	19.11066
2019	18.6671