Oil revenue, the financial lifeline of Venezuela, is quickly drying up, adding to the growing instability of Nicolas Maduro’s embattled regime.

Crude exports that once accounted for 95 percent of foreign currency inflow to the country tumbled by almost half this month, after hitting a 73-year low in May. The plunge comes as U.S. sanctions continue to target Venezuela, home of the world’s largest oil reserves.

Maduro’s regime is already plagued by a humanitarian crisis aggravated by the pandemic that’s sapping domestic demand for fuels. There’s only one more oil tanker expected to load for the remaining 12 days of the month, documents show. Venezuela used to load two vessels per day two years ago before financial sanctions were imposed.