Year	Percent change (Units)
1980	9.870
1981	17.286
1982	-22.498
1983	3.097
1984	5.626
1985	4.884
1986	38.784
1987	30.280
1988	42.837
1989	-2.743
1990	10.812
1991	10.812
1992	10.812
1993	10.812
1994	5.677
1995	9.813
1996	10.201
1997	21.148
1998	24.791
1999	11.032
2000	-4.329
2001	3.640
2002	5.240
2003	3.160
2004	11.786
2005	11.769
2006	9.631
2007	17.208
2008	3.543
2009	-12.738
2010	8.079
2011	7.171
2012	3.650
2013	4.141
2014	3.628
2015	3.544
2016	3.148
2017	6.027
2018	2.890
2019	1.257
2020	-9.505
2021	10.879
2022	6.906
2023	-0.203
2024	3.956
2025	4.303
2026	4.239
2027	3.815
2028	3.839
2029	3.754