A company uses straight$-$line depreciation with the following information for $2015$ and $2016$:

Property, plant and equipment for $2015$ and $2016$ are $$15,000$ and $$25,000.$ Accumulated depreciation for $2015$ and $2016$ are $$5,000$ and $$10,000.$ Depreciation expense are $$2000,$ and $$3,000.$ Net sales for $2015$ and $2016$ are $$60,000$ and $$62,500.$ Calculate the average age of the company$$s property, plant, and equipment for $2016.$