Year	Percent
1990	39.077
1991	39.843
1992	40.587
1993	41.219
1994	40.646
1995	40.05
1996	39.508
1997	38.988
1998	38.489
1999	38.004
2000	37.516
2001	36.977
2002	36.401
2003	36.129
2004	36.275
2005	36.188
2006	36.945
2007	37.868
2008	38.42
2009	38.976
2010	39.495
2011	40.344
2012	41.118
2013	41.894
2014	42.542
2015	43.084
2016	43.52
2017	43.767
2018	44.001
2019	44.226
2020	44.446
2021	44.701
2022	44.949
2023	45.184
2024	45.397
2025	45.585
2026	45.788
2027	45.969
2028	46.13
2029	46.279
2030	46.425