Year	Percent
1990	45.497
1991	45.348
1992	45.236
1993	45.113
1994	45.003
1995	44.875
1996	44.754
1997	44.681
1998	44.836
1999	44.763
2000	44.655
2001	44.541
2002	44.374
2003	44.221
2004	44.087
2005	44.005
2006	43.851
2007	43.702
2008	43.048
2009	43.62
2010	43.455
2011	45.033
2012	46.348
2013	48.997
2014	49.946
2015	50.319
2016	50.596
2017	50.794
2018	50.98
2019	51.148
2020	51.292
2021	51.413
2022	51.509
2023	51.581
2024	51.628
2025	51.65
2026	51.65
2027	51.626
2028	51.581
2029	51.517
2030	51.439