What was the percentage change in weighted-average price per share between 2019 and 2020?
{"Aggregate purchase price (1)": {"January 31, 2020": 1334.0, "February 1, 2019": 42.0, "February 2, 2018": 1449.0}, "Class A common stock repurchased": {"January 31, 2020": 7664.0, "February 1, 2019": 286.0, "February 2, 2018": 13977.0}, "Weighted-average price per share": {"January 31, 2020": 174.02, "February 1, 2019": 148.07, "February 2, 2018": 103.66}}
weighted_average_price_per_share_2020 = df["Weighted-average price per share"]["January 31, 2020"]
weighted_average_price_per_share_2019 = df["Weighted-average price per share"]["February 1, 2019"]
answer = (weighted_average_price_per_share_2020 - weighted_average_price_per_share_2019) / weighted_average_price_per_share_2019 * 100.0