What is the percentage change in pro forma revenue from 2018 to 2019? 
{"Pro forma revenue": {"2019": 86206, "2018": 78130}, "Pro forma net income (loss)": {"2019": 889, "2018": -12268}}
pro_forma_revenue_2019 = df["Pro forma revenue"]["2019"]
pro_forma_revenue_2018 = df["Pro forma revenue"]["2018"]
answer = ( pro_forma_revenue_2019 - pro_forma_revenue_2018 ) / pro_forma_revenue_2018 * 100.0