Adjusted for temperature variations

The adjustment is based on degree days, i.e. the number of degrees the temperature on a particular day is below 18 degrees centigrade. All these differences per day are added together. In 2012, there were 2,879 degree days, versus 3,078 in 2013, adjusted on the basis of the average number of degree days (2,949) over the period 1981-2010.