Year	Percent
1990	20.294
1991	20.241
1992	21.373
1993	20.834
1994	19.927
1995	18.497
1996	16.847
1997	16.643
1998	15.257
1999	17.149
2000	12.947
2001	12.012
2002	13.646
2003	13.195
2004	12.757
2005	12.331
2006	11.951
2007	15.037
2008	16.021
2009	15.257
2010	15.163
2011	14.25
2012	14.751
2013	15.532
2014	15.356
2015	16.385
2016	16.159
2017	16.284
2018	16.409
2019	16.534
2020	16.659
2021	16.783
2022	16.908
2023	17.033
2024	17.158
2025	17.283
2026	17.408
2027	17.533
2028	17.658
2029	17.783
2030	17.907