How do you calculate the percentage of change in sales from 20X8 to 20X9? This will go in cell D7? Please show the formula so it is understood how to get the answer. thank you

Kretsmart
Common-Size Income Statements
For the Years Ended December 31, 20'X'9, 20'X'8, 20'X'7
	20'X'9			20'X'8			20'X'7
		Year-to-Year	% Sales		Year-to-Year	% Sales		% Sales
Net Sales	1,000,000			700,000			600,000
Cost of goods sold	710,000			500,000			430,000
Gross profit on sales	290,000			200,000			170,000
Operating expenses	240,000			160,000			120,000
Operating income	50,000			40,000			50,000
Interest expense	22,000			22,000			22,000
Income (loss) before income tax	28,000			18,000			28,000
Income tax expense (refund)	13,000			6,000			9,000
Net income (loss)	15,000			12,000			19,000