Year	Percent
1990	8.116
1991	8.182
1992	8.252
1993	8.325
1994	8.398
1995	8.472
1996	8.558
1997	8.644
1998	9.229
1999	9.85
2000	10.507
2001	11.201
2002	11.931
2003	12.696
2004	13.495
2005	14.504
2006	15.593
2007	16.761
2008	18.016
2009	18.025
2010	18.05
2011	18.121
2012	18.229
2013	18.313
2014	18.36
2015	18.418
2016	18.483
2017	18.725
2018	18.964
2019	19.198
2020	19.426
2021	19.651
2022	19.874
2023	20.093
2024	20.308
2025	20.517
2026	20.722
2027	20.921
2028	21.118
2029	21.315
2030	21.512