Did you read what is written under the table in the source you provided? Results of the last census shows an increase in the sense of separative ethnicity of some regional communities in Poland, although 
 in most cases this involves simultaneous self-determination with the Polish nationality. The largest non-Polish national-ethnic identification include declarations of Silesian and Kashubian etnicity. 
 The total reported response to the first or second ethnic question - is 847 thousand for the Silesian declarations, with less than half (376 ths.) that expressed it as their single identification, more often it was declared jointly with Polish nationality - 431 thousand. (See Table. 2).