Jorgansen Lighting, Incorporated, manufactures heavy$-$duty street lighting systems for municipalities. The company uses variable costing for internal management reports and absorption costing for external reports. The company provided the following data:

Year $1$ Year $2$ Year $3$

Inventories

Beginning $($units$)210160180$

Ending $($units$)160180220$

Variable costing net operating income $ $290,000$ $ $279,000$ $ $250,000$

The company$$s fixed manufacturing overhead per unit was constant at $$570$ for all three years.