Year	Percent change (Units)
1980	-6.300
1981	9.132
1982	-11.310
1983	-45.625
1984	-25.588
1985	-13.939
1986	-0.781
1987	6.500
1988	-12.487
1989	8.185
1990	24.819
1991	33.174
1992	-12.003
1993	-1.141
1994	13.472
1995	-4.096
1996	35.505
1997	3.124
1998	17.723
1999	16.580
2000	18.590
2001	106.192
2002	17.860
2003	19.764
2004	26.768
2005	9.479
2006	15.232
2007	-8.645
2008	13.380
2009	-5.259
2010	-5.322
2011	24.588
2012	30.028
2013	13.677
2014	-5.013
2015	-3.117
2016	0.531
2017	33.988
2018	4.109
2019	-7.968
2020	-19.021
2021	27.175
2022	31.177
2023	-1.676
2024	0.581
2025	3.216
2026	1.327
2027	33.649
2028	21.194
2029	9.742