Year	Percent
1990	10.8
1991	11.07
1992	10.58
1993	9.75
1994	10.73
1995	9.95
1996	9.77
1997	9.86
1998	10.29
1999	9.81
2000	9.51
2001	9.43
2002	10.39
2003	11.6
2004	11.7
2005	12.11
2006	12.09
2007	12.94
2008	14.17
2009	15.17
2010	16.04
2011	16.45
2012	16.91
2013	17.61
2014	18.24
2015	18.05
2016	17.92
2017	18.167
2018	18.415
2019	18.662
2020	18.91
2021	19.157
2022	19.405
2023	19.652
2024	19.9
2025	20.147
2026	20.395
2027	20.642
2028	20.89
2029	21.137
2030	21.385