Year	Percent
1990	61.179
1991	61.264
1992	60.968
1993	60.785
1994	60.545
1995	60.324
1996	60.135
1997	59.974
1998	59.797
1999	59.406
2000	58.888
2001	58.405
2002	57.888
2003	57.292
2004	56.702
2005	56.106
2006	55.502
2007	54.943
2008	54.452
2009	53.959
2010	53.504
2011	53.208
2012	52.859
2013	52.481
2014	52.114
2015	51.763
2016	51.454
2017	51.269
2018	51.087
2019	50.917
2020	50.763
2021	50.626
2022	50.508
2023	50.4
2024	50.293
2025	50.178
2026	50.066
2027	49.951
2028	49.832
2029	49.709
2030	49.58