Year	Percent
1990	21.786
1991	22.017
1992	22.231
1993	22.305
1994	22.281
1995	22.18
1996	22.153
1997	22.094
1998	22.045
1999	22
2000	21.995
2001	21.953
2002	21.874
2003	21.745
2004	21.53
2005	21.384
2006	21.2
2007	20.967
2008	20.76
2009	18.3
2010	17.13
2011	18.33
2012	15.275
2013	12.65
2014	13.08
2015	10.92
2016	13.78
2017	13.329
2018	12.878
2019	12.427
2020	11.977
2021	11.526
2022	11.075
2023	10.624
2024	10.173
2025	9.722
2026	9.271
2027	8.821
2028	8.37
2029	7.919
2030	7.468