Year	Percent
1990	53.584
1991	53.819
1992	54.044
1993	54.301
1994	54.515
1995	54.73
1996	54.955
1997	55.069
1998	54.558
1999	54.623
2000	54.815
2001	54.695
2002	54.805
2003	54.957
2004	55.18
2005	55.362
2006	55.49
2007	55.815
2008	55.124
2009	56.577
2010	57.017
2011	59.193
2012	61.125
2013	64.684
2014	66.072
2015	67.136
2016	67.271
2017	67.558
2018	67.835
2019	68.102
2020	68.361
2021	68.613
2022	68.856
2023	69.093
2024	69.323
2025	69.548
2026	69.77
2027	69.99
2028	70.204
2029	70.411
2030	70.607