Year Percent 1990 4.153 1991 4.568 1992 4.275 1993 4.466 1994 4.543 1995 4.008 1996 4.421 1997 4.807 1998 4.552 1999 4.47 2000 4.47 2001 4.49 2002 3.91 2003 4.65 2004 4.88 2005 4.75 2006 4.4 2007 4.47 2008 4.5 2009 6.62 2010 6.31 2011 5.81 2012 4.94 2013 3.94 2014 3.72 2015 3.94 2016 4 2017 4.029 2018 4.059 2019 4.088 2020 4.118 2021 4.147 2022 4.177 2023 4.206 2024 4.236 2025 4.265 2026 4.295 2027 4.324 2028 4.354 2029 4.383 2030 4.412