<Tr> <Td> June 30, 1970 </Td> <Td> 395 </Td> <Td> + 18 </Td> </Tr> <Tr> <Td> March 17, 1971 </Td> <Td> 430 </Td> <Td> + 35 </Td> </Tr> <Tr> <Td> March 15, 1972 </Td> <Td> 450 </Td> <Td> + 20 </Td> </Tr> <Tr> <Td> October 27, 1972 </Td> <Td> 465 </Td> <Td> + 15 </Td> </Tr>

Who does the us owe for the national debt