Year	Percent
1990	47.618
1991	48.16
1992	48.68
1993	49.465
1994	50.189
1995	50.772
1996	51.11
1997	51.421
1998	50.807
1999	51.222
2000	51.534
2001	51.887
2002	50.804
2003	51.46
2004	51.899
2005	52.42
2006	53.098
2007	53.815
2008	56.218
2009	55.913
2010	57.059
2011	57.608
2012	58.417
2013	58.603
2014	59.707
2015	60.798
2016	60.629
2017	60.473
2018	60.308
2019	60.119
2020	59.901
2021	59.678
2022	59.433
2023	59.169
2024	58.894
2025	58.611
2026	58.369
2027	58.124
2028	57.875
2029	57.621
2030	57.361