Year Percent change (Units) 2000 -0.771 2001 -12.530 2002 15.041 2003 -21.161 2004 28.780 2005 -0.115 2006 -2.212 2007 1.209 2008 -4.406 2009 -1.065 2010 -10.181 2011 -3.485 2012 19.789 2013 6.840 2014 7.369 2015 5.909 2016 8.884 2017 6.000 2018 6.000 2019 5.832 2020 5.525 2021 5.448 2022 5.261 2023 5.613 2024 5.536 2025 5.477 2026 5.467 2027 5.471 2028 5.513 2029 5.493