Year	Percent
1990	50.778
1991	51.616
1992	52.542
1993	53.125
1994	53.74
1995	53.692
1996	54.346
1997	55.244
1998	55.854
1999	55.913
2000	56.189
2001	56.235
2002	55.695
2003	56.674
2004	57.668
2005	56.698
2006	57.346
2007	56.505
2008	55.671
2009	56.391
2010	53.707
2011	55.735
2012	56.055
2013	55.68
2014	54.857
2015	55.28
2016	55.345
2017	55.34
2018	55.327
2019	55.315
2020	55.311
2021	55.315
2022	55.326
2023	55.341
2024	55.355
2025	55.364
2026	55.368
2027	55.368
2028	55.363
2029	55.357
2030	55.349