Year Percent change (Units) 1980 -8.625 1981 -5.725 1982 -6.306 1983 1.535 1984 1.337 1985 0.616 1986 0.190 1987 2.513 1988 1.878 1989 0.962 1990 4.831 1991 1.498 1992 7.021 1993 5.817 1994 4.692 1995 4.733 1996 0.816 1997 3.136 1998 2.652 1999 2.164 2000 1.126 2001 0.877 2002 1.577 2003 1.565 2004 0.889 2005 2.709 2006 4.366 2007 1.846 2008 2.096 2009 -2.053 2010 2.096 2011 3.801 2012 2.834 2013 2.235 2014 1.704 2015 2.400 2016 2.515 2017 2.262 2018 2.445 2019 2.432 2020 -7.901 2021 11.904 2022 2.799 2023 3.498 2024 3.000 2025 2.300 2026 2.300 2027 2.300 2028 2.300 2029 2.300