What is the increase / (decrease) in the Fabless design companies from 2018 to 2019?
{"": {"2017": "%", "2018": "%", "2019": "%"}, "Fabless design companies": {"2017": 91.0, "2018": 92.4, "2019": 91.3}, "Integrated device manufacturers": {"2017": 9.0, "2018": 7.6, "2019": 8.7}, "Total": {"2017": 100.0, "2018": 100.0, "2019": 100.0}}
fabless_design_companies_2019 = df["Fabless design companies"]["2019"]
fabless_design_companies_2018 = df["Fabless design companies"]["2018"]
answer = fabless_design_companies_2019 - fabless_design_companies_2018