Year Percent change (Units) 1996 0.408 1997 0.271 1998 0.135 1999 1.080 2000 4.806 2001 4.331 2002 4.518 2003 3.037 2004 2.381 2005 1.993 2006 3.040 2007 3.267 2008 1.327 2009 -2.518 2010 -0.207 2011 1.449 2012 1.735 2013 0.301 2014 -0.300 2015 0.301 2016 -0.200 2017 0.501 2018 0.798 2019 0.989 2020 -0.979 2021 5.638 2022 8.240 2023 3.201 2024 2.115 2025 2.014 2026 1.950 2027 1.960 2028 1.980 2029 2.000