Year	Percent
1990	51.031
1991	51.135
1992	51.151
1993	51.087
1994	50.949
1995	50.259
1996	49.569
1997	48.88
1998	48.19
1999	47.502
2000	46.814
2001	46.737
2002	46.661
2003	46.584
2004	46.508
2005	46.431
2006	45.929
2007	45.428
2008	44.927
2009	44.428
2010	43.93
2011	44.115
2012	44.3
2013	44.078
2014	43.995
2015	44.124
2016	44.603
2017	44.371
2018	44.138
2019	43.906
2020	43.674
2021	43.442
2022	43.21
2023	42.977
2024	42.745
2025	42.513
2026	42.281
2027	42.049
2028	41.817
2029	41.584
2030	41.352