Year	Percent
1990	18.196
1991	18.197
1992	18.204
1993	18.205
1994	18.206
1995	18.207
1996	18.207
1997	18.208
1998	18.209
1999	18.209
2000	18.209
2001	18.209
2002	18.208
2003	18.208
2004	18.207
2005	18.205
2006	18.203
2007	18.2
2008	18.197
2009	18.194
2010	18.192
2011	18.19
2012	18.189
2013	18.188
2014	18.188
2015	18.187
2016	18.186
2017	18.185
2018	18.184
2019	18.182
2020	18.181
2021	18.18
2022	18.178
2023	18.177
2024	18.176
2025	18.174
2026	18.173
2027	18.172
2028	18.17
2029	18.169
2030	18.168