Year Percent change (Units) 2001 4.553 2002 -0.441 2003 2.555 2004 0.605 2005 4.510 2006 3.594 2007 8.348 2008 1.815 2009 5.035 2010 4.941 2011 6.320 2012 1.712 2013 5.340 2014 3.349 2015 5.916 2016 5.572 2017 4.825 2018 3.406 2019 4.757 2020 -5.341 2021 10.746 2022 4.278 2023 3.300 2024 3.800 2025 4.000 2026 3.900 2027 3.800 2028 3.800 2029 3.800