Year	Percent
1990	55.81
1991	56.459
1992	57.519
1993	58.659
1994	60.06
1995	60.523
1996	60.354
1997	60.026
1998	60.051
1999	60.025
2000	59.946
2001	59.909
2002	60.107
2003	59.372
2004	58.627
2005	58.955
2006	59.119
2007	58.18
2008	57.242
2009	56.338
2010	55.837
2011	56.349
2012	55.214
2013	52.674
2014	53.792
2015	53.197
2016	51.699
2017	51.665
2018	51.611
2019	51.505
2020	51.328
2021	51.112
2022	50.835
2023	50.509
2024	50.152
2025	49.781
2026	49.423
2027	49.053
2028	48.691
2029	48.365
2030	48.091