|
| year | consumption | change |
| 1980 | .01 | NA |
| 1981 | .01 | -8.10 % |
| 1982 | .01 | 28.16 % |
| 1983 | .01 | 12.22 % |
| 1984 | .01 | 16.29 % |
| 1985 | .01 | -13.30 % |
| 1986 | .01 | 26.32 % |
| 1987 | .02 | 18.53 % |
| 1988 | .02 | 0.36 % |
| 1989 | .02 | 0.66 % |
| 1990 | .02 | 7.68 % |
| 1991 | .02 | 21.89 % |
| 1992 | .02 | 7.54 % |
| 1993 | .02 | -3.36 % |
| 1994 | .03 | 19.00 % |
| 1995 | .03 | 12.16 % |
| 1996 | .03 | 12.72 % |
| 1997 | .04 | 7.98 % |
| 1998 | .05 | 34.22 % |
| 1999 | .06 | 14.64 % |
| 2000 | .06 | 2.13 % |
| 2001 | .06 | 7.01 % |
| 2002 | .06 | -5.67 % |
| 2003 | .06 | 5.02 % |
| 2004 | .06 | 2.53 % |
| 2005 | .07 | 9.92 % |
| 2006 | .07 | -2.41 % |
| 2007 | .07 | 3.15 % |
| 2008 | .07 | 0.93 % |
| 2009 | .08 | 12.08 % |
| 2010 | .08 | 6.81 % |
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