<Tr> <Th> 1956 </Th> <Td> 201 / 435 </Td> <Td> </Td> </Tr> <Tr> <Th> 1958 </Th> <Td> 153 / 435 </Td> <Td> 48 </Td> </Tr> <Tr> <Th> 1960 </Th> <Td> 175 / 435 </Td> <Td> 22 </Td> <Td> John F. Kennedy </Td> </Tr> <Tr> <Th> 1962 </Th> <Td> 176 / 435 </Td> <Td> </Td> </Tr>

What is the primary purpose of the parties in the american party system (points 1)