Year	Percent
1990	13.439
1991	13.671
1992	14.031
1993	14.37
1994	14.825
1995	15.252
1996	15.639
1997	15.866
1998	15.588
1999	15.944
2000	17.323
2001	18.488
2002	18.247
2003	18.009
2004	17.773
2005	17.54
2006	17.309
2007	17.081
2008	16.855
2009	16.631
2010	16.41
2011	16.83
2012	17.072
2013	17.1
2014	17.331
2015	17.463
2016	17.656
2017	17.602
2018	17.548
2019	17.494
2020	17.44
2021	17.387
2022	17.333
2023	17.279
2024	17.225
2025	17.171
2026	17.117
2027	17.063
2028	17.01
2029	16.956
2030	16.902