Residential electrical rates on Oahu edged lower in December, reflecting a decline in fuel prices, according to Hawaiian Electric Co.

The bill for a typical household using 600 kilowatt-hours of a electricity a month is $206.20 in December, $1.96 less than in November, according to HECO. The December rate is 32.9 cents a kilowatt-hour.

Elsewhere in the state, electrical rates declined in Maui County and were unchanged on Kauai and Hawaii island.

Maui Electric Co. customers are paying 36.9 cents per kilowatt-hour in December, down from 37.6 cents a kilowatt-hour last month. Hawaii island’s residential rate is 40.6 cents a kilowatt-hour in December, and on Kauai the rate is 41.2 cents a kilowatt-hour.

The decline in Oahu’s rate was primarily due to a drop in the price for low-sulfur fuel oil, which accounts for more than 50 percent of a customer’s bill, a HECO spokesman said.

HECO is paying $132.54 a barrel for LSFO in December, compared with $133.18 a barrel in November.

The high cost of fuel oil used for power generation is a major reason why the price of electricity in Hawaii is nearly three times the national average. Hawaii residents paid an average of 36.3 cents a kilowatt-hour for electricity in September compared with the national average of 12.5 cents a kilowatt-hour, according to the latest data available from the U.S. Energy Information Administration.

Roughly 80 percent of the electricity consumed in Hawaii is generated by burning oil, the highest percentage of any state. The next-highest state is Alaska at about 14 percent, according to the EIA.

Per-capita electricity use in Hawaii is the second lowest in the nation at 614 kilowatt-hours per month, according to data compiled by the U.S. Census Bureau. Only California is lower at 560 kilowatt-hours per month.