Year	Percent
1990	43.916
1991	44.863
1992	45.668
1993	46.169
1994	46.494
1995	47.15
1996	47.611
1997	48.4
1998	48.819
1999	48.872
2000	49.546
2001	50.195
2002	50.104
2003	50.111
2004	51.625
2005	52.742
2006	53.818
2007	53.32
2008	53.854
2009	54.387
2010	54.061
2011	54.549
2012	54.174
2013	54.729
2014	54.945
2015	54.975
2016	54.15
2017	54.372
2018	54.589
2019	54.807
2020	55.029
2021	55.261
2022	55.493
2023	55.73
2024	55.979
2025	56.242
2026	56.525
2027	56.821
2028	57.125
2029	57.434
2030	57.743
