Year Percent change (Units) 1991 -0.552 1992 2.193 1993 1.569 1994 0.257 1995 1.872 1996 4.052 1997 2.886 1998 2.496 1999 0.522 2000 5.518 2001 6.667 2002 14.604 2003 9.503 2004 10.442 2005 7.008 2006 6.726 2007 7.318 2008 7.199 2009 8.353 2010 11.259 2011 4.887 2012 4.279 2013 5.394 2014 6.310 2015 2.653 2016 -1.617 2017 0.806 2018 1.923 2019 2.208 2020 -1.794 2021 3.647 2022 3.252 2023 2.860 2024 3.338 2025 2.964 2026 2.983 2027 3.340 2028 3.336 2029 3.315