Year Percent change (Units) 1999 -9.424 2000 6.132 2001 6.879 2002 6.380 2003 4.388 2004 9.028 2005 5.530 2006 5.108 2007 6.440 2008 5.656 2009 -2.732 2010 0.731 2011 2.036 2012 -0.682 2013 2.893 2014 -1.590 2015 1.806 2016 3.339 2017 2.101 2018 4.495 2019 4.332 2020 -0.903 2021 7.726 2022 2.550 2023 2.528 2024 3.465 2025 4.454 2026 4.010 2027 4.001 2028 4.025 2029 4.004