|
| year | consumption | change |
| 1980 | .03 | NA |
| 1981 | .03 | 12.53 % |
| 1982 | .03 | 6.52 % |
| 1983 | .04 | 19.67 % |
| 1984 | .04 | 1.11 % |
| 1985 | .04 | -1.05 % |
| 1986 | .04 | 2.69 % |
| 1987 | .06 | 59.53 % |
| 1988 | .11 | 75.97 % |
| 1989 | .11 | -1.18 % |
| 1990 | .11 | -1.14 % |
| 1991 | .05 | -56.09 % |
| 1992 | .03 | -32.48 % |
| 1993 | .03 | -3.62 % |
| 1994 | .03 | 0.51 % |
| 1995 | .03 | -15.33 % |
| 1996 | .03 | -0.26 % |
| 1997 | .03 | -4.23 % |
| 1998 | .02 | -2.84 % |
| 1999 | .02 | 0.93 % |
| 2000 | .02 | -4.03 % |
| 2001 | .02 | -25.84 % |
| 2002 | .02 | 3.11 % |
| 2003 | .02 | -10.64 % |
| 2004 | .02 | -1.04 % |
| 2005 | .02 | 5.33 % |
| 2006 | .02 | 9.19 % |
| 2007 | .03 | 42.93 % |
| 2008 | .03 | 11.96 % |
| 2009 | .10 | 231.08 % |
| 2010 | .10 | 6.33 % |
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