1979      4.28
1980      2.17
1981      0.06
1982      2.68
1983      2.43
1984     -2.05
1985      0.19
1986      1.60
1987      3.00
1988     -0.19
1989     -0.51
1990     -0.51
1991     -2.43
1992     -0.90
1993      0.57
1994     -0.19
1995     -2.56
1996     -3.01
1997     -0.77
1998      0.83
1999     -1.73
2000     -2.94
2001     -2.37
2002     -1.79
2003     -2.50
2004     -4.54
2005     -8.19
2006     -7.80
2007     -7.10
2008     -4.03
2009     -5.05
2010     -6.72
2011     -8.19
2012     -6.91