CREATE TABLE table_25102 ("District" CLOB, "Vacator" CLOB, "Reason for change" CLOB, "Successor" CLOB, "Date successor seated" CLOB)

Name the total number of reason for change for not filled this congress
SELECT COUNT("Reason for change") FROM table_25102 WHERE "Date successor seated" = 'Not filled this congress'
SELECT COUNT("Reason for change") FROM "table_25102" WHERE "Date successor seated" = 'Not filled this congress'