| 1st January 1986 – 31st December 2017 | 170∙5% | – |
| 1st January 1987 – 31st December 2017 | 162∙4% | – |
| 1st January 1988 – 31st December 2017 | 151∙8% | – |
| 1st January 1989 – 31st December 2017 | 138∙2% | – |
| 1st January 1990 – 31st December 2017 | 121∙4% | – |
| 1st January 1991 – 31st December 2017 | 99∙6% | – |
| 1st January 1992 – 31st December 2017 | 91∙8% | – |
| 1st January 1993 – 31st December 2017 | 85∙1% | – |
| 1st January 1994 – 31st December 2017 | 81∙8% | – |
| 1st January 1995 – 31st December 2017 | 77∙9% | – |
| 1st January 1996 – 31st December 2017 | 71∙2% | – |
| 1st January 1997 – 31st December 2017 | 67∙7% | – |
| 1st January 1998 – 31st December 2017 | 61∙9% | – |
| 1st January 1999 – 31st December 2017 | 56∙9% | – |
| 1st January 2000 – 31st December 2017 | 55∙2% | – |
| 1st January 2001 – 31st December 2017 | 50∙2% | – |
| 1st January 2002 – 31st December 2017 | 47∙7% | – |
| 1st January 2003 – 31st December 2017 | 45∙2% | – |
| 1st January 2004 – 31st December 2017 | 41∙3% | – |
| 1st January 2005 – 31st December 2017 | 37∙0% | – |
| 1st January 2006 – 31st December 2017 | 33∙4% | – |
| 1st January 2007 – 31st December 2017 | 28∙8% | – |
| 1st January 2008 – 31st December 2017 | 24∙0% | – |
| 1st January 2009 – 31st December 2017 | 18∙1% | 18∙1% |
| 1st January 2010 – 31st December 2017 | 19∙7% | 19∙7% |
| 1st January 2011 – 31st December 2017 | 16∙1% | 16∙1% |
| 1st January 2012 – 31st December 2017 | 10∙4% | 10∙4% |
| 1st January 2013 – 31st December 2017 | 8∙0% | 8∙0% |
| 1st January 2014 – 31st December 2017 | 5∙2% | 5∙2% |
| 1st January 2015 – 31st December 2017 | 3∙9% | 3∙9% |
| 1st January 2016 – 31st December 2017 | 4∙0% | 4∙0% |
| 1st January 2017 – 31st December 2017 | 3∙0% | 2∙5% |
| (all dates inclusive) | | |