|
| year | consumption | change |
| 1980 | .18 | NA |
| 1981 | .19 | 1.52 % |
| 1982 | .18 | -5.52 % |
| 1983 | .18 | 1.22 % |
| 1984 | .18 | 2.45 % |
| 1985 | .17 | -9.14 % |
| 1986 | .17 | 3.16 % |
| 1987 | .18 | 4.18 % |
| 1988 | .18 | -1.64 % |
| 1989 | .17 | -2.50 % |
| 1990 | .18 | 5.75 % |
| 1991 | .18 | -0.85 % |
| 1992 | .18 | 1.35 % |
| 1993 | .18 | -3.15 % |
| 1994 | .20 | 16.02 % |
| 1995 | .22 | 5.81 % |
| 1996 | .19 | -10.43 % |
| 1997 | .20 | 2.86 % |
| 1998 | .21 | 4.70 % |
| 1999 | .20 | -1.58 % |
| 2000 | .21 | 0.72 % |
| 2001 | .20 | -1.42 % |
| 2002 | .20 | -0.29 % |
| 2003 | .20 | -2.97 % |
| 2004 | .23 | 15.44 % |
| 2005 | .22 | -3.08 % |
| 2006 | .23 | 4.40 % |
| 2007 | .24 | 2.45 % |
| 2008 | .24 | 1.39 % |
| 2009 | .25 | 4.80 % |
| 2010 | .28 | 10.61 % |
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