Year	Percent
1991	23.525
1992	24.093
1993	24.155
1994	24.002
1995	22.463
1996	21.97
1997	19.936
1998	18.737
1999	17.537
2000	18.378
2001	19.057
2002	18.757
2003	17.575
2004	17.219
2005	16.644
2006	15.016
2007	14.169
2008	13.826
2009	13.163
2010	12.686
2011	12.249
2012	11.725
2013	10.948
2014	10.271
2015	10.372
2016	9.408
2017	9.331
2018	8.985
2019	8.667
2020	8.359
2021	8.057
2022	7.781