| Year | Interim | Final | Total | Total Increase |
|---|---|---|---|---|
| 2014 | 6.200 | 14.200 | 20.400 | 6.3% |
| 2013 | 5.900 | 13.300 | 19.200 | 6.7% |
| 2012 | 5.600 | 12.4 | 18.000 | 5.9% |
| 2011 | 5.300 | 11.700 | 17.000 | 6.3% |
| 2010 | 5.000 | 11.000 | 16.000 | 8.8% |
| 2009 | 4.800 | 9.900 | 14.700 | 0% |
| 2008 | 4.800 | 9.900 | 14.700 | 2.4% |
| 2007 | 4.450 | 9.900 | 14.350 | 10% |
| 2006 | 4.050 | 9.000 | 13.050 | 8.8% |
| 2005 | 3.750 | 8.250 | 12.000 | 9.1% |
| 2004 | 3.450 | 7.550 | 11.000 | 10% |
| 2003 | 3.150 | 6.850 | 10.000 | 8.7% |
| 2002 | 2.950 | 6.250 | 9.200 | 7% |
| 2001 | 2.750 | 5.850 | 8.600 | 7.5% |
| 2000 | 2.500 | 5.500 | 8.000 | 10.3% |
| 1999 | 2.250 | 5.000 | 7.250 | 11.5% |
| 1998 | 2.000 | 4.500 | 6.500 | 13% |
| 1997 | 1.750 | 4.000 | 5.750 | 18.6% |
| 1996 | 1.150 | 3.700 | 4.850 | 9% |
| 1995 | 1.075 | 3.375 | 4.450 | 7.9% |
| 1994 | 1.000 | 3.125 | 4.125 | 11.5% |
| 1993 | 0.900 | 2.800 | 3.700 | 13.8% |
| 1992 | 0.800 | 2.450 | 3.250 | 9.2% |
| 1991 | 0.725 | 2.250 | 2.975 | 8.2% |
| 1990 | 0.675 | 2.075 | 2.750 | 10% |
| 1989 | 0.625 | 1.875 | 2.500 | 242.5% |
| 1988 | 0.220 | 0.510 | 0.730 | 4.3% |