Year	Percent
1991	55.42
1992	55.746
1993	56.277
1994	56.597
1995	55.54
1996	55.108
1997	55.276
1998	54.966
1999	55.258
2000	55.79
2001	54.956
2002	54.166
2003	53.502
2004	52.155
2005	50.842
2006	48.407
2007	47.507
2008	48.711
2009	48.803
2010	48.434
2011	48.129
2012	47.685
2013	46.942
2014	46.703
2015	47
2016	47.336
2017	47.179
2018	46.364
2019	45.48
2020	44.647
2021	43.734
2022	42.872