| Year | |
|---|---|
| 1984 | 5.7 |
| 1985 | 4.3 |
| 1986 | 4.9 |
| 1987 | 4.5 |
| 1988 | 3.7 |
| 1989 | 2.8 |
| 1990 | 4.3 |
| 1991 | 5.0 |
| 1992 | 4.9 |
| 1993 | 0.9 |
| 1994 | 1.9 |
| 1995 | 1.9 |
| 1996 | 2.8 |
| 1997 | 1.2 |
| 1998 | -0.1 |
| 1999 | 0.1 |
| 2000 | 1.3 |
| 2001 | 1.8 |
| 2002 | 1.6 |
| 2003 | 3.6 |
| 2004 | 1.4 |
| 2005 | 1.7 |
| 2006 | 2.5 |
| 2007 | 1.2 |
| 2008 | 3.1 |
| 2009 | 3.8 |
| 2010 | 0.7 |
| 2011 | 1.8 |
| 2012 | 3.4 |
| 2013 | 1.8 |
| 2014 | 1.5 |
| 2015 | 1.6 |
| 2016 | 1.8 |
| 2017 | 1.2 |
| 2018 | 1.1 |
| 2019 | 2.2 |