Year Percent change (Units) 1996 2.796 1997 2.667 1998 1.633 1999 1.919 2000 1.839 2001 1.317 2002 -0.159 2003 -0.245 2004 1.745 2005 4.087 2006 4.396 2007 3.639 2008 6.572 2009 8.154 2010 3.618 2011 3.851 2012 6.302 2013 2.138 2014 0.724 2015 0.034 2016 -0.916 2017 0.098 2018 1.040 2019 2.209 2020 0.964 2021 1.772 2022 5.020 2023 6.210 2024 4.018 2025 2.988 2026 2.500 2027 2.075 2028 2.038 2029 2.000