<Tr> <Td> Russia </Td> <Td> 6.9 </Td> <Td> -> </Td> </Tr> <Tr> <Td> Rwanda </Td> <Td> 56.8 </Td> <Td> -> </Td> </Tr> <Tr> <Td> Saint Helena </Td> <Td> 13.7 </Td> <Td> -> </Td> </Tr> <Tr> <Td> Saint Kitts and Nevis </Td> <Td> 8.6 </Td> <Td> -> </Td> </Tr>

What is the usa's ranking in the world list of lowest infant mortality