Year Percent 1990 1.33 1991 1.38 1992 1.3 1993 1.2 1994 1.35 1995 0.98 1996 0.92 1997 1.3 1998 0.72 1999 1.11 2000 1.4 2001 1.56 2002 1.67 2003 2.15 2004 2.21 2005 2.13 2006 2.4 2007 2.77 2008 3.02 2009 3.63 2010 3.24 2011 3.02 2012 3.28 2013 3.26 2014 3.52 2015 3.76 2016 3.27 2017 3.421 2018 3.571 2019 3.722 2020 3.873 2021 4.024 2022 4.174 2023 4.325 2024 4.476 2025 4.626 2026 4.777 2027 4.928 2028 5.079 2029 5.229 2030 5.38