|
| year | consumption | change |
| 1980 | .18 | NA |
| 1981 | .07 | -61.88 % |
| 1982 | .06 | -3.65 % |
| 1983 | .09 | 33.78 % |
| 1984 | .03 | -60.35 % |
| 1985 | .03 | -3.16 % |
| 1986 | .02 | -45.27 % |
| 1987 | .02 | -4.19 % |
| 1988 | .02 | 41.88 % |
| 1989 | .02 | -18.15 % |
| 1990 | .02 | 0.99 % |
| 1991 | .02 | 2.41 % |
| 1992 | .02 | -2.06 % |
| 1993 | .02 | 6.95 % |
| 1994 | .02 | -2.34 % |
| 1995 | .02 | 5.06 % |
| 1996 | .02 | -3.66 % |
| 1997 | .03 | 19.82 % |
| 1998 | .03 | 24.35 % |
| 1999 | .08 | 141.90 % |
| 2000 | .10 | 29.44 % |
| 2001 | .13 | 29.98 % |
| 2002 | .13 | 1.76 % |
| 2003 | .13 | -0.77 % |
| 2004 | .14 | 7.75 % |
| 2005 | .16 | 10.89 % |
| 2006 | .18 | 12.03 % |
| 2007 | .18 | 2.92 % |
| 2008 | .17 | -6.75 % |
| 2009 | .18 | 7.87 % |
| 2010 | .18 | -1.33 % |
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