|
| year | consumption | change |
| 1980 | .86 | NA |
| 1981 | .75 | -13.27 % |
| 1982 | .74 | -1.32 % |
| 1983 | .70 | -5.35 % |
| 1984 | .72 | 2.80 % |
| 1985 | .81 | 13.26 % |
| 1986 | .82 | 0.13 % |
| 1987 | .83 | 2.13 % |
| 1988 | .81 | -3.23 % |
| 1989 | .75 | -6.56 % |
| 1990 | .77 | 2.22 % |
| 1991 | .85 | 9.87 % |
| 1992 | .79 | -5.99 % |
| 1993 | .84 | 5.91 % |
| 1994 | .88 | 4.28 % |
| 1995 | .88 | 0.70 % |
| 1996 | .98 | 10.83 % |
| 1997 | .94 | -3.75 % |
| 1998 | .92 | -2.21 % |
| 1999 | .89 | -2.95 % |
| 2000 | .88 | -2.05 % |
| 2001 | .89 | 1.45 % |
| 2002 | .86 | -3.55 % |
| 2003 | .90 | 4.86 % |
| 2004 | .87 | -3.72 % |
| 2005 | .85 | -2.28 % |
| 2006 | .90 | 6.58 % |
| 2007 | .89 | -1.82 % |
| 2008 | .84 | -4.91 % |
| 2009 | .79 | -5.66 % |
| 2010 | .83 | 4.55 % |
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