Consolidated Satements of Income (in thousands)
	2016	2015	2014
Revenue
Net sales	60,144	64,063	61,529
Cost of goods sold	45,835	43,155	41,072
Gross profit/(loss)	14,309	20,908	20,457
Gross margin
Operating expenses
Sales and markering	4,733	4,537	3,944
Engineering and product development	3,141	2,992	2,339
General and administrative	1,913	1,601	1,392
Total operating expenses	9,787	9,130	7,675
Operating income/loss	4,522	11,778	12,782
Other income/expense
Interest income/expense	1,747	175	80
Other income/(expense)	(6,254)	(2,914)	(3,080)
Income before provision for income taxes	15	9,039	9,782
Income taxes	1,459	1,729	535
Net income/(loss)	(1,444)	7,310	9,247
Net margin

Please show how to calculate the gross and net margins from the years presented. . Show step by step on excel.