Year	Percent
1990	41.762
1991	42.635
1992	43.376
1993	43.826
1994	44.107
1995	44.713
1996	45.116
1997	45.841
1998	46.209
1999	46.22
2000	46.835
2001	47.419
2002	47.284
2003	47.24
2004	48.661
2005	49.688
2006	50.674
2007	50.207
2008	50.672
2009	51.095
2010	50.62
2011	50.996
2012	50.584
2013	51.015
2014	51.112
2015	51.027
2016	50.117
2017	50.242
2018	50.357
2019	50.464
2020	50.564
2021	50.672
2022	50.774
2023	50.871
2024	50.964
2025	51.052
2026	51.153
2027	51.253
2028	51.353
2029	51.453
2030	51.556