What is the percentage change in the net cash provided by operating activities between 2018 and 2019?
{"Net cash provided by operating activities": {"2019": 64846, "2018": 72130, "2017": 41165}, "Net cash used in investing activities": {"2019": -296780, "2018": -83448, "2017": -26387}, "Net cash provided by financing activities": {"2019": 9042, "2018": 397255, "2017": 6783}, "Effect of exchange rate changes": {"2019": 169, "2018": -800, "2017": -724}, "Net (decrease) increase in cash, cash equivalents, and restricted cash": {"2019": -222723, "2018": 385137, "2017": 20837}}
net_cash_2019 = df["Net cash provided by operating activities"]["2019"]
net_cash_2018 = df["Net cash provided by operating activities"]["2018"]
answer = (net_cash_2019 - net_cash_2018) / net_cash_2018 * 100.0