# year    value 
 1980 -0.6872467 
 1981 -0.4637714 
 1982 -0.736579 
 1983 -0.947096 
 1984 -0.9046923 
 1985 -0.8173648 
 1986 -0.7006372 
 1987 -0.4308413 
 1988 -0.2421873 
 1989 -0.394726 
 1990 -0.006756082 
 1991 -0.2411925 
 1992 -0.6778738 
 1993 -0.4279923 
 1994 -0.4416344 
 1995 -0.1687204 
 1996 -0.005303209 
 1997 -0.08206979 
 1998 0.2890303 
 1999 0.2033305 
 2000 0.3207756 
 2001 0.2852446 
 2002 0.4912892 
 2003 0.4523959 
 2004 0.513916 
 2005 0.4741522