|
| year | consumption | change |
| 1980 | .09 | NA |
| 1981 | .08 | -3.59 % |
| 1982 | .08 | -0.46 % |
| 1983 | .06 | -32.97 % |
| 1984 | .05 | -7.10 % |
| 1985 | .06 | 13.57 % |
| 1986 | .08 | 33.31 % |
| 1987 | .09 | 9.28 % |
| 1988 | .09 | 9.59 % |
| 1989 | .10 | 10.40 % |
| 1990 | .10 | -2.53 % |
| 1991 | .10 | 3.95 % |
| 1992 | .11 | 8.63 % |
| 1993 | .11 | -5.89 % |
| 1994 | .12 | 7.83 % |
| 1995 | .12 | 1.77 % |
| 1996 | .12 | 5.55 % |
| 1997 | .12 | -1.37 % |
| 1998 | .10 | -21.79 % |
| 1999 | .12 | 21.79 % |
| 2000 | .14 | 23.11 % |
| 2001 | .14 | -0.67 % |
| 2002 | .13 | -7.89 % |
| 2003 | .13 | -4.02 % |
| 2004 | .14 | 15.54 % |
| 2005 | .15 | 3.05 % |
| 2006 | .15 | 0.52 % |
| 2007 | .13 | -11.24 % |
| 2008 | .15 | 11.83 % |
| 2009 | .17 | 15.70 % |
| 2010 | .19 | 12.89 % |
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