What is the change in the Gross Profit from 2018 to 2019?
{"Revenue": {"2019": 200882.0, "2018": 147094.0, "2017": 104352.0, "2016": 76846.0, "2015": 58720.0}, "Cost of revenue(1)": {"2019": 63535.0, "2018": 46810.0, "2017": 31503.0, "2016": 23767.0, "2015": 19789.0}, "Gross profit": {"2019": 137347.0, "2018": 100284.0, "2017": 72849.0, "2016": 53079.0, "2015": 38931.0}, "Operating expenses: -- Sales and marketing(1)": {"2019": 87731.0, "2018": 69608.0, "2017": 46998.0, "2016": 34847.0, "2015": 25925.0}, "Operating expenses: -- Research and development(1)": {"2019": 50024.0, "2018": 41305.0, "2017": 22241.0, "2016": 14765.0, "2015": 11521.0}, "Operating expenses: -- General and administrative(1)": {"2019": 46820.0, "2018": 31462.0, "2017": 22895.0, "2016": 14293.0, "2015": 12272.0}, "Operating expenses: -- Total operating expenses": {"2019": 184575.0, "2018": 142375.0, "2017": 92134.0, "2016": 63905.0, "2015": 49718.0}, "Operating expenses: -- Operating loss": {"2019": -47228.0, "2018": -42091.0, "2017": -19285.0, "2016": -10826.0, "2015": -10787.0}, "Operating expenses: -- Other expenses, net": {"2019": -4597.0, "2018": -4628.0, "2017": -302.0, "2016": -484.0, "2015": -599.0}, "Operating expenses: -- Loss before income taxes": {"2019": -51825.0, "2018": -46719.0, "2017": -19587.0, "2016": -11310.0, "2015": -11386.0}, "Operating expenses: -- (Provision for) benefit from income taxes": {"2019": -425.0, "2018": -796.0, "2017": -47.0, "2016": 24.0, "2015": 562.0}, "Operating expenses: -- Net loss": {"2019": -52250.0, "2018": -47515.0, "2017": -19634.0, "2016": -11286.0, "2015": -10824.0}, "Operating expenses: -- Net loss per share attributable to common shareholders - basic and diluted": {"2019": -1.58, "2018": -1.63, "2017": -0.7, "2016": -0.68, "2015": -0.88}, "Operating expenses: -- Weighted average shares outstanding - basic and diluted": {"2019": 33161656.0, "2018": 29107267.0, "2017": 27862375.0, "2016": 16659561.0, "2015": 12257413.0}}
gross_profit_2019 = df["Gross profit"]["2019"]
gross_profit_2018 = df["Gross profit"]["2018"]
answer = gross_profit_2019 - gross_profit_2018