|
| year | consumption | change |
| 1980 | .09 | NA |
| 1981 | .09 | 1.18 % |
| 1982 | .09 | 3.55 % |
| 1983 | .09 | -2.11 % |
| 1984 | .11 | 18.29 % |
| 1985 | .10 | -10.51 % |
| 1986 | .10 | 2.73 % |
| 1987 | .10 | 4.85 % |
| 1988 | .10 | -3.99 % |
| 1989 | .10 | -3.68 % |
| 1990 | .11 | 10.62 % |
| 1991 | .11 | -0.32 % |
| 1992 | .11 | 1.76 % |
| 1993 | .12 | 10.97 % |
| 1994 | .14 | 14.65 % |
| 1995 | .15 | 7.51 % |
| 1996 | .15 | -0.35 % |
| 1997 | .16 | 10.50 % |
| 1998 | .17 | 3.95 % |
| 1999 | .18 | 7.23 % |
| 2000 | .19 | 5.29 % |
| 2001 | .19 | -1.55 % |
| 2002 | .19 | 1.22 % |
| 2003 | .20 | 6.31 % |
| 2004 | .20 | -0.68 % |
| 2005 | .22 | 10.16 % |
| 2006 | .22 | -1.38 % |
| 2007 | .22 | 2.72 % |
| 2008 | .22 | -0.09 % |
| 2009 | .22 | 0.84 % |
| 2010 | .23 | 1.69 % |
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