I took some steps to reduce my heating cost this past winter, and it seems to have worked. My gas bill for the past year is $725. I have a gas water heater that seems to cost $20 a month to run, so my heating cost approximates to $485 for the winter. (I also have a finished attic heated with electric baseboards, but the cost is pretty low - maybe $50 extra in electricity for a season.)
This tool says there were 4185 heating degree days in 2015 at my house. So, to normalize it, I spent ($485 + $50)/4185 = $0.13 per HDD this past winter. I have a ~2000 square foot house and steam radiator heat fired with natural gas.
What's your cost per HDD, how do you heat your house, and how big is it?
My gas bill for the winter before this one was $1000. I replaced a leaky door, but I think most importantly, I insulated all of the steam pipes in my basement. This project cost about $200, but it appears to have already paid off.