Year	Percent
1991	16.714
1992	20.446
1993	20.025
1994	19.897
1995	19.648
1996	19.628
1997	19.78
1998	19.961
1999	19.65
2000	19.31
2001	19.542
2002	19.465
2003	19.486
2004	19.242
2005	21.446
2006	21.622
2007	19.477
2008	15.994
2009	14.645
2010	14.673
2011	14.169
2012	13.113
2013	12.984
2014	11.847
2015	12.097
2016	12.37
2017	12.334
2018	12.328
2019	12.32
2020	12.311
2021	12.301
2022	12.29