|
| year | consumption | change |
| 1980 | .02 | NA |
| 1981 | .01 | -28.80 % |
| 1982 | .01 | 14.19 % |
| 1983 | .01 | -4.94 % |
| 1984 | .01 | 9.66 % |
| 1985 | .01 | 5.33 % |
| 1986 | .02 | 6.96 % |
| 1987 | .01 | -10.05 % |
| 1988 | .02 | 29.44 % |
| 1989 | .02 | 0.40 % |
| 1990 | .02 | 9.11 % |
| 1991 | .02 | 7.68 % |
| 1992 | .02 | 11.20 % |
| 1993 | .02 | -4.73 % |
| 1994 | .02 | 9.89 % |
| 1995 | .02 | 1.60 % |
| 1996 | .03 | 2.79 % |
| 1997 | .03 | 6.57 % |
| 1998 | .03 | 7.75 % |
| 1999 | .03 | 0.24 % |
| 2000 | .03 | 12.21 % |
| 2001 | .04 | 6.67 % |
| 2002 | .04 | 4.26 % |
| 2003 | .04 | 7.53 % |
| 2004 | .04 | 3.41 % |
| 2005 | .04 | 2.64 % |
| 2006 | .04 | -6.36 % |
| 2007 | .04 | 11.36 % |
| 2008 | .04 | 1.96 % |
| 2009 | .06 | 35.29 % |
| 2010 | .06 | 4.31 % |
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