|
| Year | Result | Explanatory Note |
|---|
| 1999 | 0.69 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2000 | 0.70 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2001 | 0.72 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2002 | 0.63 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2003 | 0.55 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2004 | 0.51 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2005 | 0.47 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2006 | 0.42 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2007 | 0.38 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2008 | 0.38 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2009 | 0.32 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2010 | 0.31 | This is calculated on a calendar year basis, with data being reported during the first quarter of the following calendar year. |
| 2011 | 0.27 | |
| 2012 | 0.26 | |
| 2013 | 0.22 | |
| 2014 | 0.22 | |
| 2015 | 0.18 | |
| 2016 | 0.19 | |
| 2017 | 0.20 | |
| 2018 | 0.21 | |
| 2019 | | |