|
| year | consumption | change |
| 1980 | .02 | NA |
| 1981 | .02 | 1.58 % |
| 1982 | .01 | -6.87 % |
| 1983 | .01 | -2.51 % |
| 1984 | .01 | 3.00 % |
| 1985 | .02 | 32.18 % |
| 1986 | .02 | 6.03 % |
| 1987 | .02 | 13.76 % |
| 1988 | .02 | 7.31 % |
| 1989 | .03 | 14.31 % |
| 1990 | .03 | 16.91 % |
| 1991 | .03 | 3.73 % |
| 1992 | .04 | 14.24 % |
| 1993 | .04 | -5.55 % |
| 1994 | .04 | 7.21 % |
| 1995 | .04 | 8.47 % |
| 1996 | .04 | -7.55 % |
| 1997 | .04 | 4.84 % |
| 1998 | .05 | 13.78 % |
| 1999 | .05 | 2.09 % |
| 2000 | .06 | 19.13 % |
| 2001 | .05 | -10.70 % |
| 2002 | .05 | 1.21 % |
| 2003 | .05 | -3.73 % |
| 2004 | .06 | 14.14 % |
| 2005 | .06 | 7.33 % |
| 2006 | .06 | 1.45 % |
| 2007 | .06 | -2.47 % |
| 2008 | .06 | 4.45 % |
| 2009 | .07 | 2.76 % |
| 2010 | .07 | 14.06 % |
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