def clean_population_stats(data_frame):
    """
    Clean our population dataframe. Rename some columns, drop some columns etc..
    :param data_frame: population dataframe
    :return: pandas dataframe, cleaned
    """
    df_pop = data_frame.drop(["Country Code", "Indicator Name", "Indicator Code", "Unnamed: 63"], axis=1)
    df_pop = df_pop.rename(columns={"Country Name": "country"})
    df_pop = df_pop.melt(id_vars=["country"], var_name="year", value_name="total_population")

    df_pop["year"] = df_pop["year"].astype("float")

    return df_pop