|
| year | consumption | change |
| 1980 | .04 | NA |
| 1981 | .04 | 11.86 % |
| 1982 | .04 | -1.60 % |
| 1983 | .04 | -7.29 % |
| 1984 | .04 | 6.53 % |
| 1985 | .04 | 1.63 % |
| 1986 | .05 | 14.42 % |
| 1987 | .05 | -7.56 % |
| 1988 | .05 | 6.01 % |
| 1989 | .05 | 2.90 % |
| 1990 | .05 | 9.55 % |
| 1991 | .05 | -8.68 % |
| 1992 | .05 | 4.36 % |
| 1993 | .05 | 2.50 % |
| 1994 | .05 | -7.38 % |
| 1995 | .05 | -0.89 % |
| 1996 | .05 | 5.14 % |
| 1997 | .05 | -6.68 % |
| 1998 | .05 | 14.66 % |
| 1999 | .06 | 5.86 % |
| 2000 | .06 | 0.00 % |
| 2001 | .07 | 17.89 % |
| 2002 | .08 | 9.68 % |
| 2003 | .08 | 1.34 % |
| 2004 | .08 | 7.11 % |
| 2005 | .09 | 10.68 % |
| 2006 | .09 | 3.50 % |
| 2007 | .11 | 17.11 % |
| 2008 | .12 | 6.91 % |
| 2009 | .12 | 5.70 % |
| 2010 | .12 | -2.95 % |
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