|
| year | consumption | change |
| 1980 | .15 | NA |
| 1981 | .15 | -0.09 % |
| 1982 | .15 | -0.29 % |
| 1983 | .16 | 3.00 % |
| 1984 | .16 | 1.22 % |
| 1985 | .16 | 0.09 % |
| 1986 | .16 | -1.97 % |
| 1987 | .16 | -0.25 % |
| 1988 | .16 | 2.78 % |
| 1989 | .15 | -7.03 % |
| 1990 | .11 | -28.16 % |
| 1991 | .09 | -14.02 % |
| 1992 | .08 | -10.19 % |
| 1993 | .06 | -29.30 % |
| 1994 | .07 | 17.41 % |
| 1995 | .08 | 10.22 % |
| 1996 | .08 | 11.28 % |
| 1997 | .08 | -8.93 % |
| 1998 | .08 | 8.06 % |
| 1999 | .09 | 13.34 % |
| 2000 | .10 | 1.62 % |
| 2001 | .09 | -4.77 % |
| 2002 | .10 | 3.89 % |
| 2003 | .11 | 20.31 % |
| 2004 | .12 | 1.76 % |
| 2005 | .12 | 3.79 % |
| 2006 | .12 | -1.98 % |
| 2007 | .10 | -12.93 % |
| 2008 | .11 | 6.24 % |
| 2009 | .12 | 5.00 % |
| 2010 | .13 | 8.67 % |
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