Year	Percent
1990	30.598
1991	30.596
1992	30.601
1993	30.641
1994	30.612
1995	30.683
1996	30.742
1997	30.724
1998	30.767
1999	30.858
2000	30.898
2001	30.886
2002	30.877
2003	30.87
2004	30.868
2005	30.872
2006	30.905
2007	30.94
2008	30.98
2009	31.028
2010	31.088
2011	31.164
2012	31.249
2013	31.397
2014	31.537
2015	31.651
2016	31.728
2017	31.78
2018	31.831
2019	31.882
2020	31.933
2021	31.983
2022	32.033
2023	32.083
2024	32.131
2025	32.177
2026	32.22
2027	32.261
2028	32.301
2029	32.344
2030	32.388