Year Percent change (Units) 2001 3.589 2002 4.087 2003 8.017 2004 2.210 2005 1.612 2006 5.232 2007 8.639 2008 7.427 2009 -0.209 2010 5.178 2011 13.174 2012 10.935 2013 9.451 2014 0.849 2015 0.646 2016 -1.470 2017 0.523 2018 2.294 2019 0.892 2020 0.488 2021 3.775 2022 7.005 2023 8.420 2024 3.508 2025 2.200 2026 2.000 2027 2.000 2028 2.000 2029 2.000