<Tr> <Th> 2012 </Th> <Td> 69,598 </Td> </Tr> <Tr> <Th> 2013 </Th> <Td> 79,383 </Td> </Tr> <Tr> <Th> 2014 </Th> <Td> 84,201 </Td> </Tr> <Tr> <Th> 2015 </Th> <Td> 87,250 </Td> </Tr>

What were the key factors driving the development of big business in the united states