1979      4.45
1980      2.42
1981     -0.88
1982      2.55
1983      2.23
1984     -0.82
1985      1.98
1986      2.10
1987      1.28
1988      2.42
1989     -1.45
1990      0.83
1991     -1.58
1992     -1.77
1993      0.83
1994     -1.07
1995     -2.72
1996     -3.93
1997     -1.07
1998     -0.56
1999     -2.21
2000     -3.04
2001     -0.88
2002     -1.96
2003     -1.64
2004     -4.44
2005     -6.40
2006     -8.37
2007     -6.98
2008     -3.36
2009     -3.86
2010     -4.06
2011     -7.55
2012     -3.42