1979     12.45
1980    -18.78
1981    -13.57
1982     13.41
1983     -2.89
1984     -3.85
1985     -3.44
1986     -5.35
1987      0.81
1988     -6.18
1989     -6.18
1990      2.45
1991      2.59
1992      1.63
1993     -1.66
1994      5.06
1995      6.56
1996      9.44
1997     -2.89
1998      3.55
1999      0.40
2000      6.43
2001      3.00
2002     -4.26
2003      6.43
2004      6.70
2005      2.73
2006    -10.01
2007     -3.98
2008     18.89
2009     14.51
2010      0.12
2011     -7.68
2012      9.16