Year	Percent
1990	10.223
1991	10.224
1992	10.221
1993	10.216
1994	10.225
1995	10.244
1996	10.256
1997	10.294
1998	10.352
1999	10.41
2000	10.487
2001	10.571
2002	10.513
2003	12.027
2004	13.722
2005	14.14
2006	14.596
2007	15.25
2008	15.967
2009	15.74
2010	14.841
2011	16.597
2012	17.409
2013	17.285
2014	18.119
2015	19.038
2016	19.249
2017	19.521
2018	19.789
2019	20.036
2020	20.252
2021	20.445
2022	20.61
2023	20.753
2024	20.881
2025	20.999
2026	21.111
2027	21.213
2028	21.311
2029	21.409
2030	21.511