|
| year | consumption | change |
| 1980 | | NA |
| 1981 | | NA |
| 1982 | | NA |
| 1983 | | NA |
| 1984 | | NA |
| 1985 | | NA |
| 1986 | | NA |
| 1987 | | NA |
| 1988 | | NA |
| 1989 | | NA |
| 1990 | | NA |
| 1991 | | NA |
| 1992 | .29 | NA |
| 1993 | .24 | -16.72 % |
| 1994 | .23 | -3.79 % |
| 1995 | .19 | -18.72 % |
| 1996 | .23 | 20.47 % |
| 1997 | .22 | -4.93 % |
| 1998 | .22 | 0.19 % |
| 1999 | .24 | 7.95 % |
| 2000 | .24 | 2.31 % |
| 2001 | .23 | -5.63 % |
| 2002 | .19 | -15.31 % |
| 2003 | .20 | 5.68 % |
| 2004 | .21 | 3.94 % |
| 2005 | .21 | -0.79 % |
| 2006 | .22 | 2.48 % |
| 2007 | .20 | -5.75 % |
| 2008 | .18 | -12.54 % |
| 2009 | .21 | 16.58 % |
| 2010 | .20 | -2.58 % |
|
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