Year	Percent
1990	16.832
1991	16.793
1992	16.761
1993	16.807
1994	16.848
1995	17.762
1996	18.707
1997	19.691
1998	20.717
1999	21.786
2000	20.371
2001	19.028
2002	17.76
2003	16.564
2004	15.436
2005	14.378
2006	13.387
2007	12.462
2008	11.6
2009	10.797
2010	10.049
2011	8.848
2012	7.8
2013	6.884
2014	6.084
2015	6.133
2016	6.171
2017	5.998
2018	5.823
2019	5.648
2020	5.471
2021	5.294
2022	5.116
2023	4.935
2024	4.751
2025	4.561
2026	4.368
2027	4.171
2028	3.972
2029	3.771
2030	3.569