Year	Percent
1990	55.912
1991	56.872
1992	57.928
1993	59.363
1994	60.626
1995	61.741
1996	62.494
1997	63.176
1998	62.558
1999	63.584
2000	64.542
2001	65.563
2002	65.396
2003	66.847
2004	67.633
2005	68.444
2006	69.203
2007	69.982
2008	73.296
2009	73.753
2010	74.645
2011	75.926
2012	76.856
2013	77.298
2014	78.462
2015	79.604
2016	79.799
2017	80.059
2018	80.327
2019	80.59
2020	80.842
2021	81.09
2022	81.33
2023	81.566
2024	81.807
2025	82.056
2026	82.316
2027	82.581
2028	82.851
2029	83.121
2030	83.389
