Year	Percent
1990	52.297
1991	52.157
1992	51.779
1993	51.408
1994	51.111
1995	50.786
1996	50.74
1997	50.53
1998	50.345
1999	50.173
2000	50.077
2001	50.005
2002	49.89
2003	49.773
2004	49.683
2005	49.483
2006	49.261
2007	49.041
2008	48.979
2009	49.2
2010	47.71
2011	49.835
2012	51.96
2013	50
2014	49.343
2015	48.686
2016	48.03
2017	48.048
2018	48.067
2019	48.085
2020	48.104
2021	48.122
2022	48.141
2023	48.159
2024	48.178
2025	48.196
2026	48.215
2027	48.233
2028	48.252
2029	48.27
2030	48.289