Year	Percent change (Units)
1980	20.500
1981	10.400
1982	14.900
1983	15.982
1984	17.060
1985	12.108
1986	23.900
1987	25.185
1988	15.185
1989	20.129
1990	21.219
1991	14.737
1992	21.142
1993	11.042
1994	9.046
1995	9.361
1996	7.095
1997	6.167
1998	5.041
1999	3.745
2000	2.849
2001	2.417
2002	2.258
2003	3.412
2004	8.151
2005	8.703
2006	4.292
2007	10.882
2008	11.742
2009	16.161
2010	11.658
2011	11.056
2012	8.692
2013	6.916
2014	10.093
2015	10.988
2016	10.212
2017	23.534
2018	20.851
2019	13.875
2020	5.700
2021	4.500
2022	8.500
2023	24.392
2024	32.547
2025	25.705
2026	13.142
2027	10.795
2028	7.971
2029	6.058