Year | Value | 2020 | 17.23024000646 | 2019 | 18.673320719596 | 2018 | 17.964723644068 | 2017 | 17.704583236954 | 2016 | 17.452090515953 | 2015 | 17.424363638152 | 2014 | 15.927577955522 | 2013 | 16.570488170466 | 2012 | 16.463143807428 | 2011 | 17.110885478626 | 2010 | 17.808302223387 | 2009 | 18.472226039652 | 2008 | 19.416051068343 |
|