Year	Percent
1990	31.537
1991	31.972
1992	31.163
1993	30.85
1994	34.74
1995	36.5
1996	35.47
1997	34.453
1998	33.45
1999	32.14
2000	26.137
2001	20.91
2002	16.25
2003	17.151
2004	18.091
2005	19.07
2006	20.09
2007	20.15
2008	20.275
2009	20.4
2010	22.2
2011	20.5
2012	21.5
2013	19.9
2014	19.9
2015	19.9
2016	19.254
2017	19.272
2018	19.289
2019	19.307
2020	19.324
2021	19.342
2022	19.359
2023	19.377
2024	19.394
2025	19.412
2026	19.429
2027	19.447
2028	19.464
2029	19.481
2030	19.499