|
| year | consumption | change |
| 1980 | .00 | NA |
| 1981 | .00 | 47.76 % |
| 1982 | .01 | 35.36 % |
| 1983 | .01 | 34.94 % |
| 1984 | .01 | 50.95 % |
| 1985 | .01 | -12.12 % |
| 1986 | .01 | 24.98 % |
| 1987 | .01 | 2.01 % |
| 1988 | .01 | 0.77 % |
| 1989 | .01 | 0.28 % |
| 1990 | .01 | -4.45 % |
| 1991 | .01 | -0.87 % |
| 1992 | .01 | -2.20 % |
| 1993 | .01 | -6.60 % |
| 1994 | .01 | -13.17 % |
| 1995 | .01 | 5.64 % |
| 1996 | .01 | 0.53 % |
| 1997 | .01 | 0.09 % |
| 1998 | .01 | 1.57 % |
| 1999 | .01 | -5.57 % |
| 2000 | .01 | -2.72 % |
| 2001 | .01 | -0.65 % |
| 2002 | .01 | 5.73 % |
| 2003 | .01 | 20.87 % |
| 2004 | .01 | 0.37 % |
| 2005 | .01 | 8.20 % |
| 2006 | .02 | 8.86 % |
| 2007 | .02 | 0.06 % |
| 2008 | .02 | 8.20 % |
| 2009 | .02 | -3.44 % |
| 2010 | .02 | 0.48 % |
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