# year    value 
 1980 0.1057272 
 1981 0.112068 
 1982 -0.01002218 
 1983 -0.2322527 
 1984 -0.0397001 
 1985 0.1079707 
 1986 0.1124405 
 1987 0.2137133 
 1988 0.3686837 
 1989 0.3091318 
 1990 0.3016905 
 1991 0.2152797 
 1992 -0.1712298 
 1993 0.07633471 
 1994 0.3349176 
 1995 0.3838442 
 1996 0.4023549 
 1997 0.5234706 
 1998 0.6334035 
 1999 0.6179003 
 2000 0.7566449 
 2001 0.8053899 
 2002 0.8232455 
 2003 0.8344796 
 2004 0.7862956 
 2005 0.8702458