Year	Percent
1990	52.936
1991	52.879
1992	52.792
1993	52.702
1994	52.593
1995	52.487
1996	52.432
1997	52.374
1998	52.313
1999	52.237
2000	52.14
2001	52.053
2002	51.966
2003	51.879
2004	51.792
2005	51.706
2006	51.619
2007	51.532
2008	51.445
2009	51.358
2010	51.271
2011	51.184
2012	51.097
2013	51.01
2014	50.945
2015	50.879
2016	50.839
2017	50.761
2018	50.684
2019	50.606
2020	50.529
2021	50.451
2022	50.373
2023	50.296
2024	50.218
2025	50.141
2026	50.063
2027	49.985
2028	49.908
2029	49.83
2030	49.753