def file_percentage_parser(line):
    """
    Parses lines of the following form: extracts only the seconds part

        File duration: 5248.68s (100.00%)

    :param line: string
    :return: float containing the duration for the file in percentage
    """
    is_ = line.find('(')
    ie_ = line.find('%')
    try:
        return float(line[is_ + 1:ie_])
    except:
        return 0.0
