def _get_zip_urls(year):
    """Return urls for zip files based on pattern.

    Parameters
    ----------
    year : string
        4 digit year in string format 'YYYY'.

    Returns
    -------
    dict
    """

    suffix = f'oesm{year[2:]}'
    code = 4

    return {
        'national': f'https://www.bls.gov/oes/special.requests/{suffix}'
            'nat.zip',
        'state': f'https://www.bls.gov/oes/special.requests/{suffix}'
            'st.zip',
        'area': f'https://www.bls.gov/oes/special.requests/{suffix}ma.zip',
        'industry': f'https://www.bls.gov/oes/special.requests/{suffix}in'
            f'{code}.zip'}