1979      6.87
1980    -11.55
1981     -5.47
1982      4.35
1983     -5.66
1984     -2.95
1985      1.54
1986     -8.56
1987     -3.88
1988     -3.51
1989      4.44
1990     -3.32
1991      3.60
1992     -3.04
1993     -0.98
1994      2.38
1995      3.88
1996      7.53
1997      1.36
1998      2.10
1999      1.82
2000      9.02
2001      2.48
2002     -6.69
2003      6.40
2004      2.38
2005      2.57
2006     -4.82
2007     -3.32
2008      7.62
2009      6.87
2010      7.62
2011      1.17
2012      2.38