1998 | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | |
12.7 | 12.4 | 12.8 | 12.7 | 12.9 | 12.3 | 12.3 | 12.4 | 12.5 | 12.4 | 14 | 15.6 | 16.7 | 18.7 | 22.1 | 21.9 | 23.7 | 22.2 | 22.3 | 23.3 | 22 | 18 | 18.2 | 20 | 20.1 | 20.6 | |
33.7 | 34 | 35.1 | 34.2 | 36.5 | 37.1 | 37.1 | 35.9 | 35.1 | 33 | 33.8 | 35.1 | 36.9 | 39.6 | 41.7 | 43.4 | 42.9 | 42.2 | 43.4 | 40.3 | 38.2 | 35.8 | 36 | 35.4 | 35.4 | 36.5 |