Year Percent change (Units) 1980 12.259 1981 7.556 1982 12.058 1983 8.346 1984 4.847 1985 7.054 1986 -2.700 1987 -2.850 1988 4.191 1989 -0.322 1990 -0.807 1991 2.502 1992 -1.991 1993 0.614 1994 24.720 1995 7.772 1996 6.109 1997 2.929 1998 4.911 1999 -1.080 2000 -0.169 2001 4.727 2002 2.300 2003 2.040 2004 -0.400 2005 6.409 2006 2.336 2007 -0.233 2008 10.668 2009 0.864 2010 -0.608 2011 2.769 2012 3.817 2013 0.525 2014 -0.258 2015 1.653 2016 0.441 2017 1.483 2018 1.956 2019 -3.233 2020 1.885 2021 3.908 2022 13.779 2023 0.942 2024 2.100 2025 2.000 2026 2.000 2027 2.000 2028 2.000 2029 2.000