Energy Usage Pie-Chart
This chart is a bit difficult to read, well the blue section is. However the important bits are in yellow and red. This totals 84% of your total utility cost.
So, get your utility bills out and follow the instructions on the Costs Table. What ever your final figure is there then multiply by 84% (or multiply by 84 then divided by 100). That is the cost of heating hot water in your premises.
You can also get a good idea of the costs of utilities and other information from: