|
| year | consumption | change |
| 1980 | .03 | NA |
| 1981 | .03 | -0.38 % |
| 1982 | .03 | -0.21 % |
| 1983 | .03 | 2.98 % |
| 1984 | .03 | 12.72 % |
| 1985 | .04 | 4.90 % |
| 1986 | .04 | 2.05 % |
| 1987 | .04 | 8.95 % |
| 1988 | .04 | -5.81 % |
| 1989 | .04 | 2.64 % |
| 1990 | .04 | 1.38 % |
| 1991 | .04 | -0.71 % |
| 1992 | .04 | 5.10 % |
| 1993 | .04 | 0.23 % |
| 1994 | .04 | -2.97 % |
| 1995 | .05 | 16.44 % |
| 1996 | .05 | 3.96 % |
| 1997 | .04 | -5.44 % |
| 1998 | .04 | 0.58 % |
| 1999 | .05 | 1.16 % |
| 2000 | .05 | 0.68 % |
| 2001 | .05 | 0.46 % |
| 2002 | .06 | 32.68 % |
| 2003 | .07 | 14.11 % |
| 2004 | .07 | -1.13 % |
| 2005 | .07 | 1.59 % |
| 2006 | .07 | 4.06 % |
| 2007 | .07 | 0.88 % |
| 2008 | .08 | 14.87 % |
| 2009 | .06 | -31.18 % |
| 2010 | .06 | 1.38 % |
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