Heating with gas is absolutely not a thing in Sweden, I don't think even a single percentage point of homes use that. Firewood is way more common (it's relatively commonplace in the countryside still). Gas is used for stoves in some older buildings in a few specific cities but is almost extinct in that application too. Heating with gas hasn't really been a thing historically either - at first it was mostly wood, then coal and wood, and then district heating and fuel oil completely took over from the 1950's. For a while in the 1970's resistive electric heaters were popular because electricity was cheap with the then-new nuclear plants, while the oil crisis made oil expensive. That didn't last very long.