Year	Percent
1990	50.63
1991	50.466
1992	50.235
1993	49.984
1994	49.747
1995	49.536
1996	49.382
1997	49.238
1998	49.132
1999	49
2000	49.502
2001	50.005
2002	50.507
2003	51.01
2004	51.512
2005	52.014
2006	51.966
2007	51.963
2008	51.919
2009	51.876
2010	51.829
2011	51.74
2012	51.585
2013	51.405
2014	51.216
2015	51.039
2016	50.848
2017	50.942
2018	51.035
2019	51.128
2020	51.222
2021	51.315
2022	51.409
2023	51.502
2024	51.596
2025	51.689
2026	51.782
2027	51.876
2028	51.969
2029	52.063
2030	52.156