Why is Singapore electricity pegged to the price of oil??

The latest inflation news is that the electricity tariff is increasing by about 5.5%. The electricity tariff is pegged to the price of oil, which has been increasing explosively for the past few years.

Aside from the unreliability of the calculation of electricity bills, there's another big problem. According to the Singapore Energy Market Authority (EMA), 80% of Singapore's electricity demand is generated from natural gas. The question is why is the price of electricity not pegged to the price of natural gas, but to the price of oil?? Although natural gas prices are related in the long run to oil prices, it does not follow closely to the price explosion. Furthermore, we have a much more liberal market in the natural gas market that will keep prices down.

Therefore, the million dollar question is why is the price of electricity pegged to oil instead of natural gas??