What is the percentage change in share-based compensation for research and development between 2018 and 2019?
{"Cost of revenues": {"2019": 8741, "2018": 4982, "2017": 3735}, "Research and development": {"2019": 23132, "2018": 14975, "2017": 9550}, "Sales and marketing": {"2019": 38325, "2018": 27324, "2017": 16015}, "General and administrative": {"2019": 31156, "2018": 20807, "2017": 12760}, "Total share-based compensation expense": {"2019": 101354, "2018": 68088, "2017": 42060}}
research_and_development_2019 = df["Research and development"]["2019"]
research_and_development_2018 = df["Research and development"]["2018"]
answer = ( research_and_development_2019 - research_and_development_2018 ) / research_and_development_2018 * 100.0