|
| year | consumption | change |
| 1980 | .13 | NA |
| 1981 | .14 | 10.12 % |
| 1982 | .13 | -4.83 % |
| 1983 | .15 | 14.11 % |
| 1984 | .17 | 9.05 % |
| 1985 | .17 | 2.10 % |
| 1986 | .18 | 5.89 % |
| 1987 | .17 | -6.74 % |
| 1988 | .18 | 6.35 % |
| 1989 | .20 | 13.74 % |
| 1990 | .20 | -0.88 % |
| 1991 | .20 | -2.15 % |
| 1992 | .19 | -3.50 % |
| 1993 | .20 | 4.55 % |
| 1994 | .24 | 19.13 % |
| 1995 | .21 | -10.63 % |
| 1996 | .23 | 8.82 % |
| 1997 | .27 | 15.94 % |
| 1998 | .29 | 7.22 % |
| 1999 | .29 | 0.83 % |
| 2000 | .30 | 3.97 % |
| 2001 | .34 | 11.72 % |
| 2002 | .34 | 0.66 % |
| 2003 | .33 | -2.27 % |
| 2004 | .33 | 0.87 % |
| 2005 | .36 | 7.38 % |
| 2006 | .33 | -6.93 % |
| 2007 | .29 | -11.76 % |
| 2008 | .31 | 6.55 % |
| 2009 | .30 | -4.22 % |
| 2010 | .31 | 2.95 % |
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