|
| year | consumption | change |
| 1980 | .07 | NA |
| 1981 | .06 | -14.86 % |
| 1982 | .06 | 1.49 % |
| 1983 | .06 | 8.55 % |
| 1984 | .05 | -14.21 % |
| 1985 | .06 | 12.08 % |
| 1986 | .07 | 7.71 % |
| 1987 | .07 | 0.17 % |
| 1988 | .07 | 9.03 % |
| 1989 | .07 | 5.07 % |
| 1990 | .08 | 7.11 % |
| 1991 | .08 | -2.53 % |
| 1992 | .09 | 8.89 % |
| 1993 | .08 | -0.89 % |
| 1994 | .10 | 22.26 % |
| 1995 | .11 | 5.86 % |
| 1996 | .11 | 3.71 % |
| 1997 | .12 | 8.51 % |
| 1998 | .14 | 15.81 % |
| 1999 | .15 | 7.27 % |
| 2000 | .16 | 3.20 % |
| 2001 | .17 | 7.75 % |
| 2002 | .17 | -0.61 % |
| 2003 | .18 | 4.49 % |
| 2004 | .19 | 10.19 % |
| 2005 | .20 | 5.21 % |
| 2006 | .20 | -1.06 % |
| 2007 | .21 | 3.67 % |
| 2008 | .20 | -5.86 % |
| 2009 | .21 | 8.11 % |
| 2010 | .21 | 0.00 % |
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