Winter isn't over yet so it's hard to know what is yet to come. But at this point I'd estimate I will use about a third to a half less than last year. My house is always warm. The women like it that way - I find that to be a really great excuse to keep the house warm
I had a strange one a few days ago. The temps were in the 50's so I had the stove running really low. I'd forgotten to put more coal in it and when I realized, there was not a lot of fire left. It was late at night and I considered just letting it go out but opted to throw some more coal in. Well it looked like I'd killed the fire but being so warm out I didn't care, the house was plenty warm. I left the stove with the damper wide open and the bottom door wide open - in the "revive the fire setting" - Heck, the fire was dead.
The stove sat like that for about two days. The weather was so warm out I wasn't going to start it again until needed. Then I get home from work and the temps are dropping so I figure it's time to start a new fire. I got together all the things to start up a new fire and go over to the stove to open the door to clean it out and build a wood fire in it but when I touched it I realized it was still pretty warm. I look at the surface thermometer and the darned thing was running at about 125*F! I looked inside and the fire was coming back to life. I gave the grates a couple easy shakes just to get any ash blocking the airflow out and half an hour later the stove was back up to full operating temps!
So I was siting there thinking about all that and my only conclusion was that the gods of coal stoves were smiling on me. The fire revived at precisely the moment I wanted and needed it! But, if the fire had caught on either day while I had been at work, it could have been a very bad thing. If I had closed the stove up, the fire would have definitely gone out and I would have had to start a new fire - not really a big deal compared with some of the possible alternatives... In the future, I'll never leave the stove with everything wide open like that no matter if I think the fire is out or not. This time the gods were smiling on me, next time, they might be having a bad day...