Year	Percent change (Units)
1980	24.832
1981	16.823
1982	4.138
1983	-3.273
1984	0.032
1985	1.466
1986	-0.997
1987	3.880
1988	15.230
1989	17.600
1990	4.772
1991	-3.590
1992	4.622
1993	10.348
1994	15.144
1995	18.637
1996	7.544
1997	1.914
1998	13.936
1999	-5.957
2000	6.333
2001	16.845
2002	-8.921
2003	8.889
2004	3.628
2005	10.662
2006	8.673
2007	11.442
2008	17.016
2009	9.709
2010	0.819
2011	39.853
2012	-0.702
2013	4.266
2014	12.038
2015	8.640
2016	11.990
2017	6.623
2018	19.515
2019	4.745
2020	-2.720
2021	5.086
2022	19.693
2023	-11.470
2024	4.111
2025	17.972
2026	9.576
2027	8.986
2028	10.620
2029	11.533