| Year | Value | | 2019 | 1.6855352579569 | | 2018 | 1.5053445306194 | | 2017 | 2.632023320863 | | 2016 | 1.8418587617271 | | 2015 | 3.1150326035323 | | 2014 | 0.2579403232434 | | 2013 | -1.3186041908583 | | 2012 | 2.0808565661236 | | 2011 | 0.0094314862046048 | | 2010 | 0.89704987925012 | | 2009 | -4.2434972105625 | | 2008 | -4.6477315481833 |
|