Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_47070 ( "Region" text, "Physician (GP & specialist)" real, "Physician : Population Ratio" text, "Health Officer" real, "HO : Population Ratio" text, "All Nurses" real, "Nurse : Population Ratio" text, "Mid-wives" text, "Mid Wife: Population Ratio" text, "HEW*" text )

### Question ###
What is the number of nurses in the region with an HO : Population Ratio of 1:16,791?

### Accurate SQL ###

SELECT AVG("All Nurses") FROM table_47070 WHERE "HO : Population Ratio" = '1:16,791'