Year	Percent
1991	32.391
1992	33.616
1993	34.128
1994	34.893
1995	35.988
1996	32.702
1997	33.246
1998	35.699
1999	33.533
2000	30.986
2001	29.216
2002	25.598
2003	24.315
2004	27.495
2005	27.838
2006	28.448
2007	30.689
2008	33.302
2009	33.955
2010	34.476
2011	36.144
2012	34.772
2013	34.851
2014	35.072
2015	33.048
2016	31.654
2017	31.035
2018	30.935
2019	30.825
2020	30.696
2021	30.562
2022	30.435