|
| year | consumption | change |
| 1980 | .06 | NA |
| 1981 | .06 | 5.61 % |
| 1982 | .05 | -14.48 % |
| 1983 | .04 | -24.86 % |
| 1984 | .04 | -9.74 % |
| 1985 | .03 | -9.48 % |
| 1986 | .03 | -1.39 % |
| 1987 | .04 | 10.60 % |
| 1988 | .03 | -6.68 % |
| 1989 | .04 | 13.82 % |
| 1990 | .04 | 6.99 % |
| 1991 | .04 | -11.32 % |
| 1992 | .03 | -16.14 % |
| 1993 | .03 | -3.14 % |
| 1994 | .04 | 22.26 % |
| 1995 | .04 | 17.35 % |
| 1996 | .05 | 12.32 % |
| 1997 | .05 | -0.57 % |
| 1998 | .05 | 12.82 % |
| 1999 | .05 | -9.81 % |
| 2000 | .05 | -1.76 % |
| 2001 | .05 | -1.87 % |
| 2002 | .05 | 0.64 % |
| 2003 | .06 | 20.68 % |
| 2004 | .06 | 1.06 % |
| 2005 | .07 | 15.03 % |
| 2006 | .07 | 0.17 % |
| 2007 | .06 | -4.81 % |
| 2008 | .07 | 13.31 % |
| 2009 | .05 | -31.54 % |
| 2010 | .05 | 0.00 % |
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