Year	Percent
1990	19.073
1991	19.414
1992	19.67
1993	19.815
1994	20.143
1995	20.637
1996	20.899
1997	21.116
1998	21.471
1999	21.5
2000	21.148
2001	20.8
2002	19.8
2003	19.2
2004	17.4
2005	19.296
2006	21.346
2007	23.55
2008	25.05
2009	28.7
2010	27.9
2011	30.9
2012	32.4
2013	34.9
2014	35.448
2015	36
2016	36.116
2017	36.299
2018	36.481
2019	36.664
2020	36.847
2021	37.029
2022	37.212
2023	37.394
2024	37.577
2025	37.76
2026	37.942
2027	38.125
2028	38.308
2029	38.49
2030	38.673