Year Percent change (Units) 1990 -0.180 1991 35.717 1992 225.996 1993 85.005 1994 22.565 1995 7.794 1996 12.734 1997 33.167 1998 20.646 1999 0.389 2000 0.039 2001 3.120 2002 5.202 2003 2.363 2004 2.867 2005 2.363 2006 2.370 2007 2.960 2008 3.310 2009 2.231 2010 3.615 2011 3.443 2012 2.036 2013 1.925 2014 1.613 2015 1.868 2016 1.287 2017 1.985 2018 2.029 2019 1.411 2020 1.621 2021 2.043 2022 6.726 2023 4.769 2024 3.495 2025 2.999 2026 2.957 2027 3.003 2028 3.024 2029 2.999