Year Percent change (Units) 1990 3.696 1991 4.582 1992 1.461 1993 1.392 1994 1.325 1995 2.569 1996 3.142 1997 11.347 1998 0.872 1999 2.123 2000 3.118 2001 2.600 2002 1.849 2003 2.893 2004 1.697 2005 6.041 2006 7.922 2007 2.852 2008 6.479 2009 1.183 2010 4.291 2011 2.037 2012 0.506 2013 0.613 2014 -0.546 2015 -2.396 2016 0.028 2017 0.756 2018 -0.749 2019 -0.837 2020 -1.179 2021 1.931 2022 3.855 2023 2.070 2024 2.301 2025 2.044 2026 2.044 2027 2.044 2028 2.044 2029 2.044