|
| year | consumption | change |
| 1980 | .08 | NA |
| 1981 | .09 | 3.85 % |
| 1982 | .09 | 9.19 % |
| 1983 | .07 | -21.64 % |
| 1984 | .06 | -11.72 % |
| 1985 | .08 | 19.26 % |
| 1986 | .05 | -33.61 % |
| 1987 | .08 | 60.64 % |
| 1988 | .07 | -12.83 % |
| 1989 | .08 | 16.04 % |
| 1990 | .07 | -15.11 % |
| 1991 | .04 | -44.93 % |
| 1992 | .05 | 41.92 % |
| 1993 | .05 | -11.40 % |
| 1994 | .05 | 3.43 % |
| 1995 | .06 | 23.05 % |
| 1996 | .06 | -6.77 % |
| 1997 | .06 | 6.69 % |
| 1998 | .06 | -9.43 % |
| 1999 | .06 | 12.37 % |
| 2000 | .06 | 3.54 % |
| 2001 | .07 | 12.65 % |
| 2002 | .08 | 15.93 % |
| 2003 | .09 | 6.28 % |
| 2004 | .10 | 11.48 % |
| 2005 | .12 | 18.68 % |
| 2006 | .18 | 53.26 % |
| 2007 | .19 | 3.01 % |
| 2008 | .20 | 3.93 % |
| 2009 | .13 | -34.74 % |
| 2010 | .15 | 15.80 % |
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