Year	Percent
1991	22.965
1992	24.041
1993	23.487
1994	24.232
1995	22.04
1996	19.358
1997	19.802
1998	19.001
1999	20.112
2000	16.348
2001	15.992
2002	16.367
2003	15.94
2004	15.891
2005	15.877
2006	14.875
2007	13.756
2008	13.003
2009	12.078
2010	11.24
2011	11.074
2012	5.899
2013	5.666
2014	5.209
2015	5.051
2016	4.756
2017	4.889
2018	4.807
2019	4.707
2020	4.612
2021	4.523
2022	4.44