Year	Percent
1990	38.579
1991	44.006
1992	43.551
1993	43.189
1994	44.045
1995	44.814
1996	46.884
1997	46.847
1998	46.798
1999	46.753
2000	46.448
2001	47
2002	47.627
2003	49.611
2004	51.566
2005	53.473
2006	53.616
2007	52.397
2008	53.071
2009	51.661
2010	52.522
2011	52.734
2012	52.893
2013	52.991
2014	53.028
2015	51.66
2016	51.023
2017	51.012
2018	50.951
2019	50.844
2020	50.699
2021	50.561
2022	50.397
2023	50.22
2024	50.049
2025	49.897
2026	49.786
2027	49.704
2028	49.648
2029	49.616
2030	49.607