Year	Percent
1991	58.088
1992	57.807
1993	56.977
1994	57.032
1995	56.524
1996	56.116
1997	54.906
1998	54.077
1999	52.825
2000	53.487
2001	53.231
2002	52.924
2003	52.78
2004	52.858
2005	52.152
2006	48.861
2007	47.999
2008	47.408
2009	47.078
2010	45.852
2011	45.295
2012	46.682
2013	48.86
2014	48.513
2015	46.278
2016	44.957
2017	44.468
2018	43.596
2019	42.278
2020	41.232
2021	40.35
2022	39.496