Year	Percent
1990	10.34
1991	9.58
1992	8.76
1993	8.71
1994	9.54
1995	9.93
1996	10.91
1997	9.72
1998	8.75
1999	10.91
2000	11.76
2001	13.31
2002	14.65
2003	14.65
2004	15.72
2005	16.33
2006	17.7
2007	19.59
2008	20.58
2009	21.08
2010	22.57
2011	24.81
2012	25.59
2013	26.92
2014	27.39
2015	27.85
2016	29.16
2017	29.378
2018	29.596
2019	29.814
2020	30.032
2021	30.25
2022	30.468
2023	30.686
2024	30.904
2025	31.121
2026	31.339
2027	31.557
2028	31.775
2029	31.993
2030	32.211