Year Percent change (Units) 1980 1.809 1981 1.069 1982 2.505 1983 1.241 1984 1.514 1985 1.623 1986 2.337 1987 2.562 1988 4.743 1989 4.344 1990 2.924 1991 1.048 1992 1.599 1993 -0.629 1994 2.358 1995 2.107 1996 1.413 1997 2.336 1998 3.589 1999 3.421 2000 3.924 2001 1.984 2002 1.136 2003 0.823 2004 2.830 2005 1.663 2006 2.449 2007 2.425 2008 0.255 2009 -2.873 2010 1.949 2011 2.193 2012 0.313 2013 0.576 2014 0.956 2015 1.113 2016 1.095 2017 2.291 2018 1.865 2019 1.843 2020 -7.540 2021 6.321 2022 2.526 2023 0.869 2024 0.744 2025 1.442 2026 1.568 2027 1.464 2028 1.446 2029 1.343