Year	Percent (Units)
1980	1.187
1981	1.213
1982	1.250
1983	1.279
1984	1.308
1985	1.316
1986	1.361
1987	1.443
1988	1.409
1989	1.363
1990	1.431
1991	1.410
1992	1.345
1993	1.426
1994	1.309
1995	1.354
1996	1.394
1997	1.441
1998	1.445
1999	1.351
2000	1.379
2001	1.269
2002	1.314
2003	1.335
2004	1.392
2005	1.450
2006	1.473
2007	1.469
2008	1.439
2009	1.376
2010	1.417
2011	1.517
2012	1.536
2013	1.609
2014	1.693
2015	1.803
2016	1.817
2017	1.860
2018	1.850
2019	1.815
2020	1.904
2021	1.994
2022	2.036
2023	2.064
2024	2.064
2025	2.063
2026	2.066
2027	2.073
2028	2.081
2029	2.090