Year	Percent
1991	41.563
1992	41.801
1993	41.938
1994	43.85
1995	42.889
1996	41.68
1997	44.661
1998	42.73
1999	40.83
2000	39.464
2001	39.442
2002	39.634
2003	41.008
2004	42.4
2005	43.009
2006	44.317
2007	38.276
2008	42.264
2009	42.707
2010	42.419
2011	42.138
2012	35.359
2013	37.457
2014	40.1
2015	32.039
2016	32.268
2017	32.145
2018	32.03
2019	31.9
2020	31.767
2021	31.646
2022	31.525