Year	Percent
1990	53.681
1991	53.529
1992	53.383
1993	53.211
1994	53.06
1995	52.88
1996	52.828
1997	52.76
1998	52.662
1999	52.54
2000	51.17
2001	49.799
2002	48.428
2003	47.059
2004	45.695
2005	44.337
2006	42.987
2007	41.648
2008	40.321
2009	39.008
2010	37.711
2011	36.431
2012	35.171
2013	33.93
2014	33.838
2015	33.742
2016	33.708
2017	33.41
2018	33.112
2019	32.813
2020	32.515
2021	32.217
2022	31.919
2023	31.62
2024	31.322
2025	31.024
2026	30.725
2027	30.427
2028	30.129
2029	29.831
2030	29.532