Context: According to figures from Britain's Radio Manufacturers Association, 18,999 television sets had been manufactured from 1936 to September 1939, when production was halted by the war.

Question: How many TVs were made between 1936 and the start of the war in 1939?
Answer: 18,999

Question: How many television sets had been manufactured by 1939?
Answer: Unanswerable

Question: When did production of radio sets end?
Answer: Unanswerable

Question: What caused the halt in production of radio sets?
Answer: Unanswerable