Year Percent 1990 0.295 1991 0.298 1992 0.299 1993 0.301 1994 0.285 1995 0.269 1996 0.269 1997 0.262 1998 0.259 1999 0.263 2000 0.26 2001 0.89 2002 0.44 2003 0.98 2004 0.47 2005 0.62 2006 0.33 2007 0.36 2008 0.57 2009 1.12 2010 1.11 2011 0.53 2012 0.91 2013 1.16 2014 1.83 2015 1.84 2016 1.22 2017 1.372 2018 1.524 2019 1.676 2020 1.828 2021 1.98 2022 2.132 2023 2.284 2024 2.436 2025 2.588 2026 2.74 2027 2.892 2028 3.044 2029 3.195 2030 3.347