(CNN) The Taliban have strengthened their grip in Afghanistan over the past three years, according to a new report released by the US government's own ombudsman of the war.

In its quarterly report for the US Congress, the Special Inspector General for Afghan Reconstruction (SIGAR) said that the Afghan government currently controls or influences only 55.5% of the country's districts, marking the lowest level recorded since SIGAR began tracking district control in November 2015.

Translated into layman's terms, the report measures "control" -- in which one side runs an area -- and "influence" -- in which one side has the upper hand.

In November 2015, the Afghan government controlled 72% of districts in the country, but now controls just 56% of them. Insurgent influence or control has risen to 12.5% of districts from just 7% and approximately a third of Afghanistan is a "contested" area.

The official figures offer a glimpse into the Afghan army's loosening grip in the face of a determined, sustained Taliban insurgency and a bleak outlook for America's involvement in the war -- now in its 17th year.

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