Year Percent change (Units) 1996 -0.750 1997 3.200 1998 -2.114 1999 3.293 2000 5.836 2001 3.960 2002 0.806 2003 2.677 2004 -2.167 2005 1.092 2006 3.117 2007 6.153 2008 4.052 2009 -1.420 2010 3.032 2011 2.784 2012 4.755 2013 1.376 2014 -0.588 2015 -0.318 2016 -0.292 2017 2.435 2018 0.840 2019 0.434 2020 2.250 2021 4.868 2022 18.747 2023 3.623 2024 4.000 2025 2.000 2026 2.000 2027 2.000 2028 2.000 2029 2.000