Year	Percent
1990	48.78
1991	48.969
1992	49.176
1993	49.333
1994	49.542
1995	48.915
1996	48.306
1997	47.771
1998	48.148
1999	48.535
2000	48.916
2001	49.606
2002	50.251
2003	50.854
2004	51.424
2005	51.971
2006	52.509
2007	53.02
2008	53.519
2009	54.029
2010	54.566
2011	55.236
2012	55.941
2013	56.674
2014	57.427
2015	57.747
2016	58.016
2017	58.499
2018	58.982
2019	59.454
2020	59.904
2021	60.327
2022	60.731
2023	61.106
2024	61.436
2025	61.715
2026	61.946
2027	62.13
2028	62.291
2029	62.464
2030	62.671