National Grid's supply rates change every 6 months and the winter rate is nearly always higher than the summer. So a better comparison may be the 14.82cents/kWh from last winter's supply rate. Assuming a rough 15cents/kwh delivery fee:

550kWH last winter = $7 customer charge + (14.82 cents/kwh supply * 550) + (15 cents/kwh delivery * 550) = $170

550kWH this winter = $7 customer charge + (33.89 cents/kwh supply * 550) + (15 cents/kwh delivery * 550) = $275

This particular case would be about 73% total bill increase compared to last winter, even though the supply rate went from 14.82 to 33.89 winter over winter (229% increase)