Years			Jan-12	Jan-11	Jan-10
Net Sales			$70.395,00	$67.997,00	$66.176,00
Cost of Good Sold			46133	44693	43764
Gross Profit			24262	23304	22412
Operating Expense
Selling and administrative expenses			16028	15849	15902
Depreciation and amortization			1573	1616	1707
Total operating charge			17601	17465	17609
Operating profit			6661	5839	4803
Other Income (expense)
Interest income			(13)	(15)	(18)
Interest expense			606	530	676
Interest and other, net			593	566	821
Earnings before income taxes			6068	5273	3982
Provision for income taxes			2185	1935	1362
Net Earnings			$ 3.883,00	$ 3.338,00	$ 2.661,00
Weighted average common shares outstanding:
Basic			$ 2,49	$ 2,03	$ 1,58
Diluted			$ 2,47	$ 2,01	$ 1,57

how sales evolve from 2011 to 2012, what pace have operating cost increased or decreased in comparison and what could be causes of evolution in gross profit? 300 words minimum please