| 1st January 1986 – 31st December 2014 | 160∙3% | – |
| 1st January 1987 – 31st December 2014 | 152∙5% | – |
| 1st January 1988 – 31st December 2014 | 142∙3% | – |
| 1st January 1989 – 31st December 2014 | 129∙2% | – |
| 1st January 1990 – 31st December 2014 | 113∙0% | – |
| 1st January 1991 – 31st December 2014 | 92∙1% | – |
| 1st January 1992 – 31st December 2014 | 84∙5% | – |
| 1st January 1993 – 31st December 2014 | 78∙1% | – |
| 1st January 1994 – 31st December 2014 | 75∙0% | – |
| 1st January 1995 – 31st December 2014 | 71∙2% | – |
| 1st January 1996 – 31st December 2014 | 64∙8% | – |
| 1st January 1997 – 31st December 2014 | 61∙4% | – |
| 1st January 1998 – 31st December 2014 | 55∙8% | – |
| 1st January 1999 – 31st December 2014 | 51∙0% | – |
| 1st January 2000 – 31st December 2014 | 49∙3% | – |
| 1st January 2001 – 31st December 2014 | 44∙5% | – |
| 1st January 2002 – 31st December 2014 | 42∙1% | – |
| 1st January 2003 – 31st December 2014 | 39∙7% | – |
| 1st January 2004 – 31st December 2014 | 35∙9% | – |
| 1st January 2005 – 31st December 2014 | 31∙9% | – |
| 1st January 2006 – 31st December 2014 | 28∙4% | – |
| 1st January 2007 – 31st December 2014 | 23∙9% | – |
| 1st January 2008 – 31st December 2014 | 19∙3% | – |
| 1st January 2009 – 31st December 2014 | 13∙6% | 13∙6% |
| 1st January 2010 – 31st December 2014 | 15∙2% | 13∙1% |
| 1st January 2011 – 31st December 2014 | 11∙7% | 10∙4% |
| 1st January 2012 – 31st December 2014 | 6∙2% | 6∙2% |
| 1st January 2013 – 31st December 2014 | 3∙9% | 3∙9% |
| 1st January 2014 – 31st December 2014 | 1∙2% | 1∙2% |
| (all dates inclusive) | | |