Year Percent change (Units) 1993 840.056 1994 214.768 1995 131.326 1996 21.812 1997 11.032 1998 84.436 1999 36.558 2000 20.200 2001 18.584 2002 15.056 2003 11.988 2004 11.741 2005 10.915 2006 8.996 2007 11.869 2008 13.282 2009 8.797 2010 8.777 2011 6.101 2012 6.576 2013 6.450 2014 11.362 2015 12.908 2016 5.375 2017 2.523 2018 4.269 2019 3.046 2020 4.912 2021 8.393 2022 11.923 2023 7.417 2024 5.301 2025 4.370 2026 4.000 2027 4.000 2028 4.000 2029 4.000