|
| year | consumption | change |
| 1980 | 11.00 | NA |
| 1981 | 10.00 | -9.09 % |
| 1982 | 10.00 | 0.00 % |
| 1983 | 10.00 | 0.00 % |
| 1984 | 11.00 | 10.00 % |
| 1985 | 11.00 | 0.00 % |
| 1986 | 11.00 | 0.00 % |
| 1987 | 12.00 | 9.09 % |
| 1988 | 12.00 | 0.00 % |
| 1989 | 13.00 | 8.33 % |
| 1990 | 14.00 | 7.69 % |
| 1991 | 13.00 | -7.14 % |
| 1992 | 14.00 | 7.69 % |
| 1993 | 15.00 | 7.14 % |
| 1994 | 15.00 | 0.00 % |
| 1995 | 15.00 | 0.00 % |
| 1996 | 17.00 | 13.33 % |
| 1997 | 17.00 | 0.00 % |
| 1998 | 18.00 | 5.88 % |
| 1999 | 18.00 | 0.00 % |
| 2000 | 18.23 | 1.27 % |
| 2001 | 17.49 | -4.05 % |
| 2002 | 18.05 | 3.19 % |
| 2003 | 18.31 | 1.43 % |
| 2004 | 19.03 | 3.96 % |
| 2005 | 19.36 | 1.74 % |
| 2006 | 20.08 | 3.70 % |
| 2007 | 20.73 | 3.26 % |
| 2008 | 19.95 | -3.77 % |
| 2009 | 21.98 | 10.16 % |
| 2010 | 20.96 | -4.65 % |
| 2011 | 20.77 | -0.90 % |
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