What is the change in Net cash provided by operating activities from Fiscal Year Ended December 28, 2019 to December 29, 2018?
{"": {"December 28, 2019": "", "December 29, 2018": "(Dollars in thousands)", "December 30, 2017": ""}, "Net cash provided by operating activities": {"December 28, 2019": 121048, "December 29, 2018": 68700, "December 30, 2017": 86323}, "Net cash used in investing activities": {"December 28, 2019": -66352, "December 29, 2018": -21295, "December 30, 2017": -59425}, "Net cash used in financing activities": {"December 28, 2019": -6578, "December 29, 2018": -39329, "December 30, 2017": -39470}}
net_cash_2019 = df["Net cash provided by operating activities"]["December 28, 2019"]
net_cash_2018 = df["Net cash provided by operating activities"]["December 29, 2018"]
answer = net_cash_2019 - net_cash_2018