Year	Percent
1991	39.798
1992	39.623
1993	40.185
1994	41.938
1995	37.686
1996	40.444
1997	41.609
1998	45.988
1999	47.038
2000	45.409
2001	44.631
2002	42.798
2003	43
2004	42.774
2005	43.031
2006	44.135
2007	43.79
2008	44.332
2009	42.101
2010	40.504
2011	41.431
2012	40.037
2013	40.177
2014	38.113
2015	34.929
2016	32.178
2017	32.3
2018	31.91
2019	31.564
2020	31.297
2021	31.1
2022	30.944