What was the percentage change of the balance at the end of the period from 2018 to 2019?
{"Balance, beginning of year": {"December 29, 2019": 103884, "December 30, 2018": 105959, "December 31, 2017": 82253}, "Additions for tax positions related to the current year": {"December 29, 2019": 2517, "December 30, 2018": 2404, "December 31, 2017": 2478}, "Additions for tax positions from prior years": {"December 29, 2019": 1624, "December 30, 2018": 451, "December 31, 2017": 22151}, "Reductions for tax positions from prior years/statute of limitations expirations": {"December 29, 2019": -416, "December 30, 2018": -2468, "December 31, 2017": -1460}, "Foreign exchange (gain) loss": {"December 29, 2019": -668, "December 30, 2018": -2462, "December 31, 2017": 537}, "Balance at the end of the period": {"December 29, 2019": 106941, "December 30, 2018": 103884, "December 31, 2017": 105959}}
balance_2019 = df["Balance at the end of the period"]["December 29, 2019"]
balance_2018 = df["Balance, beginning of year"]["December 29, 2019"]
answer = (balance_2019 - balance_2018) / balance_2018 * 100.0