def get(url, params=None):
    """A basic utility to get and parse a web page."""
    req = requests.get(url, params=params)
    doc = lxml.html.fromstring(req.text)
    return doc

def get_countries(base_url, doc):
    """Takes the document and returns (country, country_value)."""
    for select in doc.cssselect('form select'):
        if select.get('name') == COUNTRY:
            for option in select.cssselect('option'):
                yield (option.text, option.get('value'))

def get_country_data(url, country_code, page=0):
    """Page through the data for one country."""
    doc = get(url, {PAGE: page, COUNTRY: country_code})

    # Get the data for the current page, counting it as we go.
    n = 0
    for table_row in doc.cssselect('table tbody tr'):
        n += 1
        yield tuple( td.text for td in table_row.cssselect('td') )

    # If this page has data, see if the next does too.
    if n > 0:
        for row in get_country_data(url, country_code, page + 1):
            yield row