Year	Percent
1991	53.198
1992	52.089
1993	52.231
1994	51.56
1995	50.994
1996	51.398
1997	52.128
1998	52.329
1999	52.849
2000	55.326
2001	56.709
2002	57.343
2003	56.73
2004	56.386
2005	55.954
2006	55.491
2007	54.836
2008	54.205
2009	55.221
2010	54.482
2011	53.049
2012	52.744
2013	52.602
2014	52.656
2015	52.415
2016	52.276
2017	52.171
2018	52.068
2019	51.959
2020	51.84
2021	51.714
2022	51.577