|
| year | consumption | change |
| 1980 | .14 | NA |
| 1981 | .13 | -10.76 % |
| 1982 | .12 | -4.91 % |
| 1983 | .11 | -4.89 % |
| 1984 | .12 | 7.87 % |
| 1985 | .13 | 1.46 % |
| 1986 | .13 | -0.33 % |
| 1987 | .12 | -0.47 % |
| 1988 | .13 | 3.64 % |
| 1989 | .14 | 7.69 % |
| 1990 | .14 | 4.24 % |
| 1991 | .16 | 8.18 % |
| 1992 | .16 | -0.59 % |
| 1993 | .16 | 4.47 % |
| 1994 | .16 | -3.64 % |
| 1995 | .14 | -11.15 % |
| 1996 | .14 | 1.89 % |
| 1997 | .14 | -0.44 % |
| 1998 | .14 | -2.00 % |
| 1999 | .15 | 5.50 % |
| 2000 | .15 | 5.36 % |
| 2001 | .16 | 4.93 % |
| 2002 | .17 | 5.23 % |
| 2003 | .18 | 5.33 % |
| 2004 | .20 | 10.35 % |
| 2005 | .21 | 4.32 % |
| 2006 | .20 | -1.22 % |
| 2007 | .20 | -2.04 % |
| 2008 | .20 | -1.69 % |
| 2009 | .19 | -5.32 % |
| 2010 | .20 | 7.13 % |
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