CREATE TABLE table_21481509_4 (COUnT VARCHAR(255), r1b1a2__r_m269_ VARCHAR(255))
How many n are listed for 0.6% r1b1a2 (r-m269)?
    
SQL: SELECT COUnT AS n FROM table_21481509_4 WHERE r1b1a2__r_m269_ = "0.6%"