What is the change in the weighted average grant date fair value of awards granted under the ESPP from 2017 to 2018?
{"Issued shares": {"2019": 1.0, "2018": 2.0, "2017": 2.3}, "Average price of issued shares": {"2019": 90.25, "2018": 39.03, "2017": 36.99}, "Weighted average grant date fair value of awards granted under the ESPP": {"2019": 42.75, "2018": 32.41, "2017": 19.2}}
weighted_average_grant_date_fair_value_of_awards_granted_under_the_ESPP_2018 = df["Weighted average grant date fair value of awards granted under the ESPP"]["2018"]
weighted_average_grant_date_fair_value_of_awards_granted_under_the_ESPP_2017 = df["Weighted average grant date fair value of awards granted under the ESPP"]["2017"]
answer = weighted_average_grant_date_fair_value_of_awards_granted_under_the_ESPP_2018 - weighted_average_grant_date_fair_value_of_awards_granted_under_the_ESPP_2017