Year	Percent
1991	31.809
1992	31.116
1993	31.331
1994	33.779
1995	33.919
1996	33.898
1997	32.78
1998	33.176
1999	32.081
2000	32.476
2001	31.968
2002	31.994
2003	31.97
2004	32.492
2005	32.148
2006	32.847
2007	32.418
2008	31.694
2009	31.144
2010	30.755
2011	30.038
2012	30.024
2013	29.981
2014	30.74
2015	32.522
2016	30.147
2017	30.209
2018	30.103
2019	29.863
2020	29.747
2021	29.649
2022	29.604