Year Percent change (Units) 1991 6.565 1992 4.759 1993 4.745 1994 5.590 1995 5.648 1996 3.190 1997 3.754 1998 2.755 1999 2.830 2000 1.689 2001 2.881 2002 1.600 2003 4.462 2004 1.256 2005 3.474 2006 3.357 2007 5.104 2008 4.084 2009 4.136 2010 3.480 2011 3.448 2012 5.373 2013 5.225 2014 4.444 2015 3.819 2016 4.217 2017 6.154 2018 7.493 2019 6.078 2020 4.881 2021 6.606 2022 10.089 2023 8.114 2024 7.241 2025 6.683 2026 7.282 2027 7.773 2028 8.592 2029 8.994