import pandas as pd

def make_histogram(rewards):
    if not rewards:
        return pd.DataFrame(columns=["Score Bins", "Frequency"])
    bins = [-0.01, 0.2, 0.4, 0.6, 0.8, 1.0]
    labels = ["0.0-0.2", "0.2-0.4", "0.4-0.6", "0.6-0.8", "0.8-1.0"]
    binned = pd.cut(rewards, bins=bins, labels=labels)
    counts = binned.value_counts().sort_index().reset_index()
    counts.columns = ["Score Bins", "Frequency"]
    return pd.DataFrame(counts)

print(make_histogram([0.0, 1.0, 0.5, 0.21, 0.25]).to_dict(orient="records"))