Simplify the following text for a Grade 8 native English-speaking person.
Original: Harold Edward Holt , CH ( 5 August 1908-17 December 1967 ) was an Australian politician and the 17th Prime Minister of Australia .
Simplified: Harold Edward Holt ( 5 August 1908 â `` 17 December 1967 ) was the 17th Prime Minister of Australia .