|
| year | consumption | change |
| 1980 | .40 | NA |
| 1981 | .36 | -10.05 % |
| 1982 | .35 | -1.01 % |
| 1983 | .38 | 7.60 % |
| 1984 | .38 | 0.90 % |
| 1985 | .42 | 9.60 % |
| 1986 | .44 | 4.96 % |
| 1987 | .45 | 2.32 % |
| 1988 | .46 | 2.66 % |
| 1989 | .48 | 3.57 % |
| 1990 | .51 | 6.08 % |
| 1991 | .53 | 4.36 % |
| 1992 | .50 | -6.74 % |
| 1993 | .44 | -10.90 % |
| 1994 | .53 | 20.01 % |
| 1995 | .55 | 4.23 % |
| 1996 | .58 | 5.66 % |
| 1997 | .62 | 5.64 % |
| 1998 | .59 | -3.96 % |
| 1999 | .56 | -5.99 % |
| 2000 | .63 | 12.95 % |
| 2001 | .67 | 5.91 % |
| 2002 | .70 | 4.48 % |
| 2003 | .68 | -1.82 % |
| 2004 | .76 | 10.76 % |
| 2005 | .77 | 1.86 % |
| 2006 | .73 | -5.25 % |
| 2007 | .76 | 3.66 % |
| 2008 | .74 | -2.71 % |
| 2009 | .78 | 5.55 % |
| 2010 | .84 | 7.87 % |
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