Year	Percent
1990	18.77
1991	18.865
1992	18.986
1993	19.15
1994	19.356
1995	20.493
1996	21.667
1997	22.889
1998	24.158
1999	25.475
2000	23.76
2001	22.127
2002	20.579
2003	19.114
2004	17.734
2005	16.44
2006	15.234
2007	14.114
2008	13.076
2009	12.115
2010	11.223
2011	10.163
2012	9.195
2013	8.312
2014	7.508
2015	7.546
2016	7.591
2017	7.405
2018	7.219
2019	7.034
2020	6.849
2021	6.666
2022	6.483
2023	6.297
2024	6.105
2025	5.906
2026	5.701
2027	5.49
2028	5.274
2029	5.058
2030	4.842