Year Percent change (Units) 1996 -3.339 1997 -6.211 1998 2.837 1999 1.129 2000 4.625 2001 1.820 2002 0.443 2003 1.763 2004 -3.190 2005 2.314 2006 -0.199 2007 -1.724 2008 -2.583 2009 1.098 2010 2.066 2011 3.784 2012 -1.694 2013 -3.676 2014 -2.586 2015 4.434 2016 0.943 2017 2.255 2018 0.064 2019 3.820 2020 -1.870 2021 3.013 2022 -0.864 2023 0.766 2024 1.052 2025 1.725 2026 1.116 2027 0.809 2028 0.734 2029 0.700