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_73368 ( "Former country name" text, "Former codes" text, "Period of validity" text, "ISO 3166-3 code" text, "New country names and codes" text )

### Question ###
Name the total number for period of validity for upper volta

### Accurate SQL ###

SELECT COUNT("Period of validity") FROM table_73368 WHERE "Former country name" = 'Upper Volta'