|
| year | consumption | change |
| 1980 | .03 | NA |
| 1981 | .03 | -3.77 % |
| 1982 | .02 | -21.27 % |
| 1983 | .02 | -14.61 % |
| 1984 | .02 | 20.99 % |
| 1985 | .02 | 5.01 % |
| 1986 | .02 | -1.37 % |
| 1987 | .02 | -2.24 % |
| 1988 | .02 | 9.30 % |
| 1989 | .03 | 9.60 % |
| 1990 | .02 | -4.82 % |
| 1991 | .03 | 2.37 % |
| 1992 | .03 | 2.94 % |
| 1993 | .03 | -1.94 % |
| 1994 | .03 | 1.05 % |
| 1995 | .03 | 1.73 % |
| 1996 | .03 | 3.18 % |
| 1997 | .03 | -7.04 % |
| 1998 | .03 | 2.52 % |
| 1999 | .03 | 2.04 % |
| 2000 | .03 | 12.10 % |
| 2001 | .03 | -1.82 % |
| 2002 | .03 | 10.51 % |
| 2003 | .03 | 3.01 % |
| 2004 | .04 | 6.71 % |
| 2005 | .04 | -0.96 % |
| 2006 | .04 | 15.83 % |
| 2007 | .04 | 1.25 % |
| 2008 | .04 | 8.40 % |
| 2009 | .04 | -5.02 % |
| 2010 | .04 | 1.06 % |
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