1979      5.31
1980     -3.86
1981     -2.50
1982      5.65
1983      2.93
1984     -7.94
1985     -5.56
1986      8.37
1987     10.07
1988     -3.86
1989      1.58
1990      2.25
1991      4.29
1992     -2.84
1993    -16.43
1994      7.01
1995     18.56
1996     -1.82
1997    -17.79
1998      1.58
1999     -1.48
2000     -3.52
2001     26.71
2002     -2.84
2003     31.47
2004     21.96
2005     -0.46
2006     -9.98
2007     -2.16
2008     31.47
2009     -0.80
2010      7.35
2011    -16.09
2012     20.26