Year	Percent
1990	27.928
1991	28.06
1992	28.322
1993	28.515
1994	28.472
1995	28.272
1996	28.545
1997	28.758
1998	28.987
1999	29.48
2000	29.914
2001	29.455
2002	30.754
2003	30.207
2004	28.171
2005	29.628
2006	29.969
2007	31.898
2008	32.92
2009	33.391
2010	34.083
2011	35.458
2012	37.462
2013	39.26
2014	40.692
2015	41.611
2016	42.338
2017	42.304
2018	42.269
2019	42.227
2020	42.171
2021	42.105
2022	42.027
2023	41.939
2024	41.851
2025	41.766
2026	41.703
2027	41.644
2028	41.59
2029	41.545
2030	41.509