1979      4.69
1980      0.78
1981      1.25
1982      2.80
1983      1.73
1984     -1.58
1985      0.11
1986      1.19
1987      2.40
1989      1.86
1990      0.72
1991     -2.59
1992     -0.83
1993      1.59
1994     -0.16
1995     -1.51
1996     -4.27
1997     -2.52
1998     -0.23
1999     -2.52
2000     -2.92
2001     -3.60
2002     -2.65
2003     -2.59
2004     -5.48
2005     -7.98
2006     -8.38
2007     -7.23
2008     -5.35
2009     -5.15
2010     -7.03
2011     -8.72
2012     -7.50
2013     -7.17