|
| year | consumption | change |
| 1980 | 28.00 | NA |
| 1981 | 30.00 | 7.14 % |
| 1982 | 28.00 | -6.67 % |
| 1983 | 30.00 | 7.14 % |
| 1984 | 29.00 | -3.33 % |
| 1985 | 30.00 | 3.45 % |
| 1986 | 31.36 | 4.54 % |
| 1987 | 35.19 | 12.21 % |
| 1988 | 36.97 | 5.05 % |
| 1989 | 36.87 | -0.25 % |
| 1990 | 30.40 | -17.57 % |
| 1991 | 25.00 | -17.76 % |
| 1992 | 24.99 | -0.06 % |
| 1993 | 28.43 | 13.78 % |
| 1994 | 29.48 | 3.69 % |
| 1995 | 28.88 | -2.01 % |
| 1996 | 30.37 | 5.13 % |
| 1997 | 27.78 | -8.51 % |
| 1998 | 26.77 | -3.65 % |
| 1999 | 30.17 | 12.68 % |
| 2000 | 32.90 | 9.07 % |
| 2001 | 21.72 | -33.97 % |
| 2002 | 23.15 | 6.54 % |
| 2003 | 22.91 | -1.01 % |
| 2004 | 26.87 | 17.28 % |
| 2005 | 27.69 | 3.04 % |
| 2006 | 27.45 | -0.86 % |
| 2007 | 24.84 | -9.49 % |
| 2008 | 28.33 | 14.02 % |
| 2009 | 26.98 | -4.74 % |
| 2010 | 27.55 | 2.09 % |
| 2011 | 23.00 | -16.51 % |
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