Year	Percent
1991	19.22473
1992	18.08345
1993	16.00003
1994	14.15253
1995	10.18002
1996	9.7209
1997	9.68672
1998	9.30009
1999	8.57557
2000	6.36209
2001	6.34442
2002	6.59643
2003	6.23566
2004	5.06224
2005	5.19325
2006	5.06396
2007	4.77654
2008	3.90164
2009	4.0545
2010	4.21693
2011	4.41235
2012	4.49333
2013	4.26201
2014	3.8583
2015	3.9016
2016	3.8945
2017	3.52597
2018	3.29392
2019	3.15637