Year	Percent (Units)
1980	1.157
1981	1.180
1982	1.176
1983	1.143
1984	1.164
1985	1.185
1986	1.173
1987	1.186
1988	1.183
1989	1.194
1990	1.165
1991	1.126
1992	1.040
1993	1.060
1994	1.079
1995	1.072
1996	1.073
1997	1.080
1998	1.100
1999	1.110
2000	1.092
2001	1.094
2002	1.108
2003	1.097
2004	1.085
2005	1.067
2006	1.041
2007	1.032
2008	1.028
2009	1.053
2010	1.025
2011	1.014
2012	0.975
2013	1.024
2014	1.012
2015	0.992
2016	1.006
2017	1.003
2018	0.996
2019	0.986
2020	0.994
2021	0.986
2022	0.991
2023	0.981
2024	0.965
2025	0.954
2026	0.945
2027	0.937
2028	0.929
2029	0.922