Year	Percent
1991	55.341
1992	56.413
1993	57.866
1994	56.337
1995	55.408
1996	54.207
1997	53.704
1998	53.559
1999	52.824
2000	51.869
2001	51.14
2002	46.377
2003	47.153
2004	46.227
2005	48.439
2006	47.728
2007	47.034
2008	45.759
2009	46.351
2010	45.631
2011	45.439
2012	45.555
2013	44.659
2014	46.578
2015	48.361
2016	48.203
2017	47.129
2018	45.597
2019	43.808
2020	41.89
2021	39.922
2022	37.981