1979     -1.31
1980      3.37
1981     -1.23
1982      5.32
1983      2.93
1984     -0.16
1985      0.72
1986      4.17
1987      1.87
1988      3.37
1989      1.69
1990      0.01
1991     -1.67
1992      4.96
1993      3.73
1994     -0.08
1995     -2.99
1996     -6.62
1997     -3.53
1998     -4.94
1999     -2.82
2000     -6.80
2001     -3.44
2002     -4.67
2003     -9.01
2004     -5.82
2005     -7.42
2006    -12.99
2007    -11.13
2008     -6.09
2009     -9.18
2010    -12.63
2011    -11.48
2012    -12.19