Year	Percent
1991	30.03546
1992	29.61351
1993	29.20582
1994	28.55587
1995	27.88749
1996	27.20099
1997	26.4593
1998	25.58365
1999	24.69264
2000	23.64014
2001	23.01147
2002	22.23209
2003	21.52572
2004	20.59299
2005	19.80384
2006	19.0011
2007	18.05505
2008	17.36746
2009	16.99522
2010	16.54511
2011	16.03808
2012	15.64244
2013	15.27003
2014	14.91188
2015	14.54241
2016	14.06187
2017	13.61414
2018	11.83892
2019	10.58921