Canada’s benchmark gas price has tumbled to a record low as production hiccups at the country’s first LNG export plant on the British Columbia coast contributed to a surplus of supply.

The price at Alberta’s AECO hub fell below zero at the start of last week, and closed at minus 81 Canadian cents per gigajoule on Friday, the lowest level in data extending back to 1999. The benchmark has been on a downward trend since hitting a high for the year of C$3.68 in early February.