|
| year | consumption | change |
| 1980 | .07 | NA |
| 1981 | .08 | 10.11 % |
| 1982 | .08 | -6.11 % |
| 1983 | .07 | -3.27 % |
| 1984 | .07 | -11.42 % |
| 1985 | .08 | 17.83 % |
| 1986 | .08 | 1.91 % |
| 1987 | .09 | 10.18 % |
| 1988 | .09 | 4.53 % |
| 1989 | .09 | 0.28 % |
| 1990 | .08 | -14.15 % |
| 1991 | .07 | -15.48 % |
| 1992 | .06 | -3.16 % |
| 1993 | .06 | -1.00 % |
| 1994 | .07 | 18.39 % |
| 1995 | .08 | 8.74 % |
| 1996 | .10 | 24.81 % |
| 1997 | .10 | -5.89 % |
| 1998 | .10 | 0.95 % |
| 1999 | .13 | 29.94 % |
| 2000 | .13 | 6.03 % |
| 2001 | .11 | -17.17 % |
| 2002 | .11 | -2.66 % |
| 2003 | .11 | 1.60 % |
| 2004 | .12 | 5.77 % |
| 2005 | .11 | -1.48 % |
| 2006 | .11 | 0.57 % |
| 2007 | .12 | 4.89 % |
| 2008 | .13 | 9.26 % |
| 2009 | .13 | -0.53 % |
| 2010 | .12 | -4.72 % |
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