Year	Percent
1990	17.497
1991	17.462
1992	17.437
1993	17.49
1994	17.54
1995	18.521
1996	19.517
1997	20.551
1998	21.624
1999	22.74
2000	21.26
2001	19.86
2002	18.537
2003	17.286
2004	16.107
2005	14.999
2006	13.964
2007	12.997
2008	12.096
2009	11.258
2010	10.479
2011	9.228
2012	8.135
2013	7.182
2014	6.349
2015	6.4
2016	6.441
2017	6.263
2018	6.083
2019	5.903
2020	5.721
2021	5.539
2022	5.356
2023	5.169
2024	4.979
2025	4.784
2026	4.585
2027	4.383
2028	4.178
2029	3.971
2030	3.763