Nigeria’s foreign exchange reserves fell to $30.01 billion by March 20, down 6.7 percent from $32.17 billion a month earlier, data from the central bank showed on Monday.

The reserves were down 21.3 percent from a year earlier, when they were $38.13 billion, the data showed. In February of 2014, it oscillated between between $41 billion and $42 billion.

A country’s reserve is usually used to gauge its state of economic health, its ability to cope with external shocks and the number of months the reserve could be used to cover imports.

Imports in Nigeria increased to $4billion in December of 2014 from $3.5billion in November of 2014. Imports in Nigeria averaged a little over $2billion from 2002 until 2014. (The figures here are based on the old exchange rate of $1=N150)