What was the absolute percentage change in the discount rate from 2018 to 2019?
{"": {"2019": "%", "2018": "%"}, "Rate of increase in salaries": {"2019": 2.4, "2018": 2.7}, "Rate of increase in pensions": {"2019": 2.8, "2018": 2.9}, "Rate of price inflation": {"2019": 2.9, "2018": 3.2}, "Discount rate": {"2019": 2.1, "2018": 2.7}}
discount_rate_2019 = df["Discount rate"]["2019"]
rate_of_increase_in_salaries_2018 = df["Rate of increase in salaries"]["2018"]
answer = discount_rate_2019 - rate_of_increase_in_salaries_2018