What was the percentage change in the total net sales between 2018 and 2019?
{"Healthcare/Life Sciences ": {"2019": 1220.0, "2018": 1039.9}, "Industrial/Commercial ": {"2019": 981.2, "2018": 917.7}, "Aerospace/Defense ": {"2019": 588.6, "2018": 445.1}, "Communications ": {"2019": 374.6, "2018": 470.8}, "Total net sales": {"2019": 3164.4, "2018": 2873.5}}
total_net_sales_2019 = df["Total net sales"]["2019"]
total_net_sales_2018 = df["Total net sales"]["2018"]
answer = ( total_net_sales_2019 - total_net_sales_2018 ) / total_net_sales_2018 * 100.0