1979      1.33
1980      2.68
1981      2.83
1982      3.50
1983      0.58
1984     -1.36
1985     -1.29
1986      0.29
1988      3.13
1987      0.00
1989      0.81
1990     -0.69
1991     -1.44
1992      0.73
1993      1.18
1994      1.26
1995     -2.86
1996     -1.66
1997     -0.54
1998     -0.76
1999     -3.61
2000     -4.13
2001     -3.91
2002     -4.06
2003     -4.06
2004     -4.80
2005     -6.67
2006     -8.17
2007     -7.27
2008     -6.30
2009     -6.38
2010    -10.04
2011     -7.35