|
| year | consumption | change |
| 1980 | .03 | NA |
| 1981 | .03 | -6.99 % |
| 1982 | .03 | 2.11 % |
| 1983 | .03 | 4.44 % |
| 1984 | .03 | 2.80 % |
| 1985 | .03 | -4.73 % |
| 1986 | .04 | 16.79 % |
| 1987 | .04 | -3.40 % |
| 1988 | .05 | 25.09 % |
| 1989 | .05 | 15.66 % |
| 1990 | .06 | 12.76 % |
| 1991 | .06 | -0.59 % |
| 1992 | .06 | 2.65 % |
| 1993 | .06 | -1.14 % |
| 1994 | .06 | 1.81 % |
| 1995 | .06 | 6.67 % |
| 1996 | .07 | 12.98 % |
| 1997 | .07 | 1.61 % |
| 1998 | .08 | 7.66 % |
| 1999 | .09 | 8.98 % |
| 2000 | .09 | -1.69 % |
| 2001 | .09 | 8.05 % |
| 2002 | .10 | 5.19 % |
| 2003 | .10 | 2.70 % |
| 2004 | .11 | 8.95 % |
| 2005 | .12 | 6.75 % |
| 2006 | .12 | 5.21 % |
| 2007 | .13 | 9.44 % |
| 2008 | .13 | -1.49 % |
| 2009 | .13 | -5.54 % |
| 2010 | .13 | 5.51 % |
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