What is the percentage of total aggregate intrinsic value of options exercised as a percentage of the aggregate intrinsic value exercisable at March 31, 2019?
{"Outstanding at March 31, 2018": {"Number of Shares": 1894, "Average Price (a)": 12.9, "Average Life (years) (b)": "-", "Aggregate Intrinsic Value": "-"}, "Options granted": {"Number of Shares": "-", "Average Price (a)": "-", "Average Life (years) (b)": "-", "Aggregate Intrinsic Value": "-"}, "Options exercised": {"Number of Shares": -326, "Average Price (a)": 13.11, "Average Life (years) (b)": "-", "Aggregate Intrinsic Value": 1944}, "Options cancelled/forfeited": {"Number of Shares": -122, "Average Price (a)": 13.22, "Average Life (years) (b)": "-", "Aggregate Intrinsic Value": 295}, "Outstanding at March 31, 2019": {"Number of Shares": 1446.0, "Average Price (a)": 12.82, "Average Life (years) (b)": 3.29, "Aggregate Intrinsic Value": 6528.0}, "Exercisable at March 31, 2019": {"Number of Shares": 1347.0, "Average Price (a)": 12.7, "Average Life (years) (b)": 3.08, "Aggregate Intrinsic Value": 6253.0}}
options_exercised = df["Options exercised"]["Aggregate Intrinsic Value"]
exercisable_at_march_31_2019 = df["Exercisable at March 31, 2019"]["Aggregate Intrinsic Value"]
answer = options_exercised / exercisable_at_march_31_2019 * 100.0