Year	Percent
1990	47.784
1991	47.624
1992	47.507
1993	47.379
1994	47.261
1995	47.123
1996	46.994
1997	46.912
1998	47.075
1999	46.997
2000	46.891
2001	46.822
2002	46.69
2003	46.561
2004	46.445
2005	46.391
2006	46.29
2007	46.187
2008	45.522
2009	46.162
2010	46.009
2011	47.781
2012	49.289
2013	52.262
2014	53.407
2015	53.931
2016	54.357
2017	54.7
2018	55.039
2019	55.369
2020	55.686
2021	55.98
2022	56.257
2023	56.515
2024	56.75
2025	56.958
2026	57.132
2027	57.277
2028	57.399
2029	57.506
2030	57.603