Year	Percent
1990	54.058
1991	54.418
1992	54.2
1993	54.107
1994	54.242
1995	53.958
1996	53.811
1997	53.42
1998	53.079
1999	52.684
2000	51.963
2001	51.594
2002	51.207
2003	50.835
2004	50.51
2005	50.211
2006	50.014
2007	49.93
2008	49.903
2009	49.858
2010	49.835
2011	49.863
2012	49.892
2013	49.911
2014	49.976
2015	50.064
2016	50.12
2017	50.201
2018	50.276
2019	50.34
2020	50.394
2021	50.415
2022	50.428
2023	50.434
2024	50.432
2025	50.422
2026	50.385
2027	50.346
2028	50.31
2029	50.283
2030	50.271