Year	Percent
1990	53.581
1991	53.494
1992	53.448
1993	53.397
1994	53.328
1995	53.276
1996	53.287
1997	53.301
1998	53.309
1999	53.31
2000	53.297
2001	53.328
2002	53.175
2003	53.18
2004	53.138
2005	53.08
2006	53.75
2007	54.418
2008	55.084
2009	55.749
2010	56.412
2011	57.072
2012	57.73
2013	57.78
2014	57.829
2015	57.879
2016	57.724
2017	57.97
2018	58.217
2019	58.464
2020	58.71
2021	58.957
2022	59.203
2023	59.45
2024	59.697
2025	59.943
2026	60.19
2027	60.436
2028	60.683
2029	60.93
2030	61.176