Year	Percent
1991	43.551
1992	45.493
1993	43.342
1994	39.435
1995	39.608
1996	39.16
1997	39.015
1998	38.087
1999	37.206
2000	29.706
2001	29.763
2002	29.579
2003	30.69
2004	29.478
2005	29.216
2006	29.26
2007	28.676
2008	27.089
2009	25.553
2010	25.3
2011	25.471
2012	24.478
2013	25.754
2014	26.045
2015	24.45
2016	25.057
2017	24.171
2018	23.838
2019	23.475
2020	23.117
2021	22.774
2022	22.583