Year Percent (Units) 1994 0.014 1995 0.014 1996 0.014 1997 0.015 1998 0.017 1999 0.017 2000 0.015 2001 0.014 2002 0.012 2003 0.013 2004 0.015 2005 0.016 2006 0.015 2007 0.014 2008 0.015 2009 0.016 2010 0.016 2011 0.017 2012 0.020 2013 0.020 2014 0.021 2015 0.023 2016 0.024 2017 0.023 2018 0.023 2019 0.022 2020 0.020 2021 0.021 2022 0.021 2023 0.019