Three countries as unknown in UserCountry.getCountry?

We were using the piwik API call ‘UserCountry.getCountry’. We found that there are 3 countries with label ‘unknown’ for the response. The way I see it in the data, the country is not detected for few but they are identified as EU or Asia Pacific regions. Is it by design? How can we get all unknown in one?

API call:,2016-06-31&format=xml&token_auth=anonymous