Year	Percent
1990	47.017
1991	46.884
1992	46.767
1993	44.754
1994	42.785
1995	40.611
1996	39.653
1997	38.668
1998	39.967
1999	40.868
2000	41.112
2001	40.864
2002	41.126
2003	42.118
2004	41.987
2005	42.918
2006	43.198
2007	42.881
2008	42.683
2009	42.791
2010	43.777
2011	43.902
2012	44.801
2013	44.908
2014	46.281
2015	47.253
2016	47.962
2017	47.911
2018	47.879
2019	47.871
2020	47.884
2021	47.892
2022	47.922
2023	47.966
2024	48.019
2025	48.078
2026	48.132
2027	48.195
2028	48.255
2029	48.287
2030	48.275