What is the increase in net sales from 2018 to 2019?
{"Net sales": {"June 1, 2019": 112396, "June 2, 2018": 107705, "June 3, 2017": 86072}, "Net income": {"June 1, 2019": 9490, "June 2, 2018": 7071, "June 3, 2017": 2804}, "Total assets": {"June 1, 2019": 128470, "June 2, 2018": 134056, "June 3, 2017": 131871}, "Total liabilities": {"June 1, 2019": 7600, "June 2, 2018": 5859, "June 3, 2017": 6543}, "Total equity": {"June 1, 2019": 120870, "June 2, 2018": 128197, "June 3, 2017": 125328}}
net_sales_2019 = df["Net sales"]["June 1, 2019"]
net_sales_2018 = df["Net sales"]["June 2, 2018"]
answer = net_sales_2019 - net_sales_2018