|
| year | consumption | change |
| 1980 | .23 | NA |
| 1981 | .22 | -4.35 % |
| 1982 | .22 | 0.85 % |
| 1983 | .22 | 2.69 % |
| 1984 | .21 | -6.29 % |
| 1985 | .22 | 6.74 % |
| 1986 | .25 | 12.39 % |
| 1987 | .25 | 0.42 % |
| 1988 | .27 | 5.19 % |
| 1989 | .30 | 11.71 % |
| 1990 | .31 | 3.95 % |
| 1991 | .32 | 3.38 % |
| 1992 | .33 | 2.25 % |
| 1993 | .30 | -7.39 % |
| 1994 | .39 | 29.10 % |
| 1995 | .37 | -4.25 % |
| 1996 | .40 | 6.68 % |
| 1997 | .41 | 1.78 % |
| 1998 | .42 | 2.35 % |
| 1999 | .44 | 5.21 % |
| 2000 | .45 | 2.26 % |
| 2001 | .48 | 7.67 % |
| 2002 | .49 | 1.44 % |
| 2003 | .49 | 0.62 % |
| 2004 | .49 | 0.22 % |
| 2005 | .50 | 1.10 % |
| 2006 | .52 | 3.78 % |
| 2007 | .53 | 2.31 % |
| 2008 | .60 | 13.19 % |
| 2009 | .64 | 7.55 % |
| 2010 | .67 | 4.61 % |
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