Year Percent change (Units) 1986 2.682 1987 11.161 1988 3.192 1989 12.250 1990 8.407 1991 0.570 1992 6.776 1993 4.371 1994 6.170 1995 1.710 1996 5.717 1997 3.818 1998 2.145 1999 -0.585 2000 2.748 2001 1.160 2002 9.869 2003 0.000 2004 15.326 2005 1.053 2006 2.083 2007 8.036 2008 8.855 2009 9.978 2010 -0.296 2011 2.868 2012 5.481 2013 -1.732 2014 0.186 2015 0.370 2016 2.256 2017 1.017 2018 5.782 2019 -0.087 2020 -3.282 2021 4.080 2022 10.813 2023 10.661 2024 1.951 2025 2.091 2026 3.000 2027 3.000 2028 3.000 2029 3.000