Cost of sales is analysed as follows:


	2021			2020			2019
Opening inventories		63,909			69,685			84,227
Purchases of raw materials		161,625			105,643			122,728
Purchases of finished products		23,169			15,161			16,477
Labour costs		80,346			71,937			86,209
Depreciation and amortisation		7,895			10,144			11,709
Third party manufacturers costs		2,172			2,829			3,919
Other manufacturing costs		15,922			14,853			17,810
Government grants related to PPE		(1,252	)		(1,192	)		(1,463	)
Closing inventories		(80,211	)		(63,909	)		(69,685	)
Total		273,575			225,151			271,931

The line item “Depreciation and amortisation” includes the depreciation expenses of property plant and equipment and right-of-use assets used in the production of finished goods. The depreciation expenses amount to 7,895, 10,144 and 11,709 for the years ended December 31, 2021, 2020 and 2019, respectively.