|
| year | consumption | change |
| 1980 | .07 | NA |
| 1981 | .08 | 11.89 % |
| 1982 | .07 | -11.62 % |
| 1983 | .08 | 2.59 % |
| 1984 | .07 | -3.21 % |
| 1985 | .07 | -8.54 % |
| 1986 | .07 | 2.11 % |
| 1987 | .07 | -1.89 % |
| 1988 | .08 | 15.79 % |
| 1989 | .09 | 12.53 % |
| 1990 | .09 | 5.96 % |
| 1991 | .09 | -1.59 % |
| 1992 | .10 | 7.54 % |
| 1993 | .08 | -13.90 % |
| 1994 | .11 | 28.34 % |
| 1995 | .12 | 13.89 % |
| 1996 | .12 | -1.70 % |
| 1997 | .14 | 11.75 % |
| 1998 | .13 | -7.26 % |
| 1999 | .14 | 12.37 % |
| 2000 | .16 | 14.70 % |
| 2001 | .14 | -10.57 % |
| 2002 | .16 | 8.42 % |
| 2003 | .20 | 26.34 % |
| 2004 | .20 | 1.91 % |
| 2005 | .20 | -0.94 % |
| 2006 | .23 | 12.84 % |
| 2007 | .23 | 3.20 % |
| 2008 | .25 | 7.04 % |
| 2009 | .23 | -7.94 % |
| 2010 | .23 | 1.23 % |
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