Year	Percent change (Units)
1980	14.804
1981	29.171
1982	0.470
1983	50.643
1984	-15.511
1985	-17.736
1986	-25.310
1987	2.238
1988	-17.303
1989	27.349
1990	25.100
1991	31.686
1992	-10.513
1993	-19.307
1994	-36.189
1995	-1.078
1996	14.825
1997	-7.662
1998	-0.242
1999	-6.711
2000	8.086
2001	24.128
2002	18.028
2003	21.942
2004	16.743
2005	5.493
2006	7.632
2007	6.396
2008	12.272
2009	5.262
2010	0.511
2011	-5.471
2012	-11.590
2013	-6.602
2014	16.919
2015	-8.526
2016	13.936
2017	10.476
2018	-19.480
2019	-3.502
2020	-21.134
2021	19.559
2022	3.809
2023	-2.192
2024	-6.435
2025	-9.425
2026	-10.251
2027	-10.636
2028	-11.073
2029	-10.636