Energy dependency is a useful indicator of how much a country relies on net imports, but it is not a complete measure of energy security.
Supplier diversification
Two countries with the same rate may have very different exposure to a single supplier.
Stocks and infrastructure
Storage, terminals and interconnections influence resilience.
Type of imported energy
Oil, gas and electricity imports create different constraints.
Why the indicator remains useful
Combined with prices, production and the energy mix, dependency becomes highly informative. See the European ranking.