|
| year | consumption | change |
| 1980 | 1.32 | NA |
| 1981 | 1.31 | -0.59 % |
| 1982 | 1.36 | 3.45 % |
| 1983 | 1.38 | 1.53 % |
| 1984 | 1.39 | 0.84 % |
| 1985 | 1.43 | 2.70 % |
| 1986 | 1.41 | -0.97 % |
| 1987 | 1.41 | -0.40 % |
| 1988 | 1.41 | 0.00 % |
| 1989 | 1.32 | -6.53 % |
| 1990 | 1.18 | -10.39 % |
| 1991 | .91 | -22.66 % |
| 1992 | .90 | -1.23 % |
| 1993 | .81 | -10.48 % |
| 1994 | .84 | 4.63 % |
| 1995 | .92 | 9.11 % |
| 1996 | .95 | 2.94 % |
| 1997 | .92 | -3.40 % |
| 1998 | .85 | -7.47 % |
| 1999 | .77 | -8.97 % |
| 2000 | .87 | 12.44 % |
| 2001 | .90 | 4.19 % |
| 2002 | .87 | -3.26 % |
| 2003 | .89 | 1.37 % |
| 2004 | .87 | -1.31 % |
| 2005 | .92 | 5.00 % |
| 2006 | .94 | 2.38 % |
| 2007 | .84 | -10.56 % |
| 2008 | .82 | -2.87 % |
| 2009 | .72 | -11.75 % |
| 2010 | .77 | 6.71 % |
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