pre_text: Results of Operations Historically, revenues and earnings may or may not be representative of future operating results due to various economic and other factors. The following table sets forth the Consolidated Statements of Operations for the periods indicated (amounts in thousands): (1) Fiscal years ended March 31, 2018 and 2017 adjusted due to the adoption of ASC 606.
table: Fiscal Years Ended March 31,
table: 2019 2018 2017
table: Net sales (1) $1,382,818 $1,200,181 $757,338
table: Operating costs and expenses:
table: Cost of sales (1) 924,276 860,744 571,944
table: Selling, general and administrative expenses 202,642 173,620 107,658
table: Research and development (1) 44,612 39,114 26,693
table: Restructuring charges 8,779 14,843 5,404
table: (Gain) loss on write down and disposal of long-lived assets 1,660 (992) 10,671
table: Total operating costs and expenses 1,181,969 1,087,329 722,370
table: Operating income (1) 200,849 112,852 34,968
table: Non-operating (income) expense:
table: Interest income (2,035) (809) (24)
table: Interest expense 21,239 32,882 39,755
table: Acquisition (gain) loss — (130,880) —
table: Change in value of TOKIN options — — (10,700)
table: Other (income) expense, net (1) 11,214 24,592 (3,871)
table: Income before income taxes and equity income (loss) from equity method investments (1) 170,431 187,067 9,808
table: Income tax expense (benefit) (1) (39,460) 9,132 4,294
table: Income before equity income (loss) from equity method investments (1) 209,891 177,935 5,514
table: Equity income (loss) from equity method investments (3,304) 76,192 41,643
table: Net income (1) $206,587 $254,127 $47,157
question: Analyse this data from a financial earnings document. What was the change in Interest expense between 2017 and 2018?