In 2019, what is the percentage constitution of sales and marketing costs among the total stock-based compensation expense?
{"Cost of revenue": {"2019": 6403, "2018": 7312, "2017": 5312}, "Research and development": {"2019": 44855, "2018": 57188, "2017": 54123}, "Sales and marketing": {"2019": 11585, "2018": 14726, "2017": 14959}, "General and administrative": {"2019": 14896, "2018": 17783, "2017": 17187}, "Total stock-based compensation expense": {"2019": 77739, "2018": 97009, "2017": 91581}}
sales_and_marketing_2019 = df["Sales and marketing"]["2019"]
total_stockbased_compensation_expense_2019 = df["Total stock-based compensation expense"]["2019"]
answer = sales_and_marketing_2019 / total_stockbased_compensation_expense_2019 * 100.0