What is the percentage increase in Research and Development expense from 2017 to 2019?
{"": {"2019": "", "2018": "", "2017": "(In thousands, except percentages)", "2018 to 2019 % change": "", "2017 to 2018 % change": ""}, "Research and Development": {"2019": 207548, "2018": 160260, "2017": 115291, "2018 to 2019 % change": 30, "2017 to 2018 % change": 39}}
rd_expense_2019 = df["Research and Development"]["2019"]
rd_expense_2017 = df["Research and Development"]["2017"]
answer = ( ( rd_expense_2019 - rd_expense_2017 ) / rd_expense_2017 ) * 100.0