Year	Percent
1990	53.03
1991	52.957
1992	52.959
1993	52.849
1994	53.074
1995	52.955
1996	52.738
1997	52.489
1998	52.317
1999	52.155
2000	52.009
2001	51.882
2002	51.804
2003	51.797
2004	51.891
2005	50.867
2006	49.809
2007	48.764
2008	47.71
2009	46.621
2010	45.441
2011	45.79
2012	43.776
2013	44.758
2014	44.671
2015	47.262
2016	45.932
2017	45.793
2018	45.606
2019	45.386
2020	45.139
2021	44.788
2022	44.412
2023	44.018
2024	43.62
2025	43.227
2026	42.778
2027	42.338
2028	41.917
2029	41.534
2030	41.197