|
| year | consumption | change |
| 1980 | .10 | NA |
| 1981 | .10 | 0.00 % |
| 1982 | .19 | 90.00 % |
| 1983 | .18 | -5.26 % |
| 1984 | .18 | 0.00 % |
| 1985 | .21 | 16.67 % |
| 1986 | .19 | -9.52 % |
| 1987 | .17 | -10.53 % |
| 1988 | .17 | 0.00 % |
| 1989 | .16 | -5.88 % |
| 1990 | .13 | -18.75 % |
| 1991 | .13 | 0.00 % |
| 1992 | .13 | 0.00 % |
| 1993 | .10 | -23.08 % |
| 1994 | .12 | 20.00 % |
| 1995 | .14 | 16.67 % |
| 1996 | .13 | -7.14 % |
| 1997 | .15 | 15.38 % |
| 1998 | .12 | -20.00 % |
| 1999 | .13 | 8.33 % |
| 2000 | .15 | 15.38 % |
| 2001 | .16 | 6.67 % |
| 2002 | .18 | 12.50 % |
| 2003 | .20 | 11.11 % |
| 2004 | .15 | -25.00 % |
| 2005 | .15 | 0.00 % |
| 2006 | .17 | 13.33 % |
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