Year	Percent
1990	12.253
1991	12.288
1992	12.334
1993	12.401
1994	12.48
1995	12.566
1996	12.642
1997	12.594
1998	12.589
1999	12.63
2000	12.716
2001	12.848
2002	13.025
2003	13.245
2004	13.502
2005	13.796
2006	14.12
2007	14.48
2008	14.88
2009	15.323
2010	15.498
2011	16.47
2012	17.503
2013	18.307
2014	16.693
2015	16.619
2016	16.539
2017	16.707
2018	16.85
2019	16.952
2020	17.003
2021	17.009
2022	16.968
2023	16.893
2024	16.802
2025	16.709
2026	16.616
2027	16.519
2028	16.435
2029	16.384
2030	16.381