What was the percentage change in the balance at the end of the year between 2019 and 2020?
{"Balance, beginning of the year": {"January 31, 2020": 966, "February 1, 2019": 1059}, "Additions to intangible assets related to business combinations": {"January 31, 2020": 622, "February 1, 2019": 154}, "Amortization expense": {"January 31, 2020": -300, "February 1, 2019": -247}, "Derecognized leasehold interest": {"January 31, 2020": -116, "February 1, 2019": "\u2014"}, "Balance, end of the year": {"January 31, 2020": 1172, "February 1, 2019": 966}}
balance_2020 = df["Balance, end of the year"]["January 31, 2020"]
balance_2019 = df["Balance, beginning of the year"]["January 31, 2020"]
answer = (balance_2020 - balance_2019) / balance_2019 * 100.0