It’s been 30 years since gasoline took such a big bite out of the family budget. When the gifts from Grandma are unloaded and holiday travel is over, the typical American household will have spent $4,155 filling up this year, a record. That is 8.4 percent of what the median family takes in, the highest share since 1981. Gas averaged more than $3.50 a gallon this year, another unfortunate record. And next year isn’t likely to bring relief. In the past, high gas prices in the United States have gone hand-in-hand with economic good times, making them less damaging to family finances. Now prices are high despite slow economic growth and weak demand.