What is the percentage change in total stock-based compensation expense in 2018 compared to 2017?
{"Research, development and other related costs": {"2019": 14643, "2018": 13168, "2017": 13277}, "Selling, general and administrative": {"2019": 16911, "2018": 17843, "2017": 20185}, "Total stock-based compensation expense": {"2019": 31554, "2018": 31011, "2017": 33462}}
total_stockbased_compensation_expense_2018 = df["Total stock-based compensation expense"]["2018"]
total_stockbased_compensation_expense_2017 = df["Total stock-based compensation expense"]["2017"]
answer = (total_stockbased_compensation_expense_2018 - total_stockbased_compensation_expense_2017) / total_stockbased_compensation_expense_2017 * 100.0