Year	Percent
1990	44.999
1991	45.045
1992	45.198
1993	45.345
1994	45.6
1995	45.822
1996	45.985
1997	46.142
1998	46.316
1999	46.493
2000	46.716
2001	46.921
2002	47.157
2003	47.386
2004	47.669
2005	47.942
2006	48.339
2007	48.81
2008	49.216
2009	49.547
2010	49.892
2011	50.251
2012	50.627
2013	51.031
2014	51.464
2015	51.908
2016	52.458
2017	52.919
2018	53.393
2019	53.86
2020	54.311
2021	54.771
2022	55.211
2023	55.628
2024	56.026
2025	56.409
2026	56.795
2027	57.163
2028	57.507
2029	57.821
2030	58.102