Year Percent change (Units) 1993 16.800 1994 12.800 1995 10.800 1996 2.397 1997 11.690 1998 10.059 1999 8.409 2000 6.619 2001 3.623 2002 5.625 2003 6.464 2004 13.969 2005 7.337 2006 12.388 2007 17.057 2008 4.090 2009 -18.386 2010 6.633 2011 5.315 2012 -3.536 2013 2.111 2014 4.157 2015 4.318 2016 6.289 2017 10.672 2018 7.086 2019 4.669 2020 -9.118 2021 17.787 2022 8.992 2023 -5.069 2024 5.184 2025 5.123 2026 4.335 2027 4.554 2028 4.504 2029 4.513