<Tr> <Td> Zambia </Td> <Td> 23.7 </Td> <Td> 18.7 </Td> <Td> 21.2 </Td> <Td> 5 </Td> <Td> 2007 </Td> <Td> </Td> </Tr> <Tr> <Td> Zimbabwe </Td> <Td> 24.6 </Td> <Td> 19.9 </Td> <Td> 22.3 </Td> <Td> 4.7 </Td> <Td> 2010 - 2011 </Td> <Td> </Td> </Tr> <Table> <Tr> <Th> Country </Th> <Th> Men </Th> <Th> Women </Th> <Th> Average </Th> <Th> Age Gap </Th> <Th> Year </Th> <Th> Source </Th> </Tr> <Tr> <Td> Brazil </Td> <Td> 30 </Td> <Td> 27 </Td> <Td> 28.5 </Td> <Td> </Td> <Td> 2013 </Td> <Td> </Td> </Tr> <Tr> <Td> Canada </Td> <Td> 31.0 </Td> <Td> 29.6 </Td> <Td> 30.3 </Td> <Td> 1.4 </Td> <Td> 2008 </Td> <Td> </Td> </Tr> <Tr> <Td> Chile </Td> <Td> 35.3 </Td> <Td> 32.6 </Td> <Td> 34 </Td> <Td> 2.7 </Td> <Td> 2013 </Td> <Td> </Td> </Tr> <Tr> <Td> Mexico </Td> <Td> 29 </Td> <Td> 26 </Td> <Td> 27.5 </Td> <Td> </Td> <Td> 2011 </Td> <Td> </Td> </Tr> <Tr> <Td> United States </Td> <Td> 29.2 </Td> <Td> 27.1 </Td> <Td> 28.2 </Td> <Td> 2.1 </Td> <Td> 2015 </Td> <Td> </Td> </Tr> </Table> <Tr> <Th> Country </Th> <Th> Men </Th> <Th> Women </Th> <Th> Average </Th> <Th> Age Gap </Th> <Th> Year </Th> <Th> Source </Th> </Tr>

What is the average age for first marriages in the united states (as of 2013)
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