Year	Percent
1990	14.961
1991	15.45
1992	16.072
1993	16.509
1994	16.97
1995	17.483
1996	17.551
1997	17.676
1998	17.818
1999	17.964
2000	18.11
2001	16.794
2002	18.024
2003	16.08
2004	16.283
2005	16.488
2006	16.704
2007	20.341
2008	19.877
2009	20.825
2010	20.785
2011	21.136
2012	20.656
2013	19.577
2014	19.594
2015	19.652
2016	19.655
2017	19.749
2018	19.846
2019	19.949
2020	20.056
2021	20.16
2022	20.268
2023	20.378
2024	20.49
2025	20.601
2026	20.72
2027	20.839
2028	20.96
2029	21.08
2030	21.198