What is the percentage change in restricted stock awards and units’ expenses from 2018 to 2019?
{"Employee stock options": {"2019": 219, "2018": 438, "2017": 1980}, "Restricted stock awards and units": {"2019": 29031, "2018": 27974, "2017": 28909}, "Employee stock purchase plan": {"2019": 2304, "2018": 2599, "2017": 2573}, "Total stock-based compensation expense": {"2019": 31554, "2018": 31011, "2017": 33462}}
restricted_stock_awards_and_units_2019 = df["Restricted stock awards and units"]["2019"]
restricted_stock_awards_and_units_2018 = df["Restricted stock awards and units"]["2018"]
answer = (restricted_stock_awards_and_units_2019 - restricted_stock_awards_and_units_2018) / restricted_stock_awards_and_units_2018 * 100.0