Table:
text: List of metropolitan areas by population
List
List
Metropolitan_area Country Rank_ Forstall_2003_est_ Official_population Year_
Santiago Chile   6683852 2012
Shanghai China 10 16650000  
Seoul South Korea 2 20550000 25721000 2012
Singapore Singapore   5312000 2012
Tokyo Japan 1 32450000 36923000 2010
Toronto Canada   5583064 2011
Washington, D.C. United States   5860342 2012

text: List of metropolitan areas by population
List
List
Metropolitan_area Country Rank_ Forstall_2003_est_ Official_population Year_
Ahmedabad India   6352254 2011
Atlanta United States   5457831 2012
Bangalore India   8728906 2011
Barcelona Spain   5357422 2012
Belo Horizonte Brazil   5504635 2012
Beijing China 19 12500000  
Berlin Germany   5097712 2012
Bogotá Colombia   9023644 2014
Buenos Aires Argentina 17 13170000 12801364 2010
Cairo Egypt 16 14450000  
Chennai India   8917749 2011
Chicago United States  9175000 9522434 2012
Dallas–Fort Worth United States   6700991 2012
Delhi India 8 18600000 21753486 2011
Dhaka Bangladesh   12797394 2008
Houston United States   6177035 2012
Hyderabad India   7749334 2011
İstanbul Turkey   14160467 2014
Jakarta Indonesia 6 18900000 28019545 2010
Karachi Pakistan 20 11800000  
Kolkata India 14 15100000 14617882 2011

text: List of metropolitan areas by population
List
List
Metropolitan_area Country Rank_ Forstall_2003_est_ Official_population Year_
Lima Peru   9735587 2014
London United Kingdom 18 12875000 13614409 2012
Los Angeles United States 13 15250000 13052921 2012
Madrid Spain   6387824 2012
Manila Philippines 11 16300000 11855975 2010
Mexico City Mexico 3 20450000 20116842 2010
Miami United States   5762717 2012
Moscow Russia 15 15000000 17000000 
Mumbai India 5 19200000 20748395 2011
Nagoya Japan   9107000 2010
New York United States 4 19750000 19831858 2012
Osaka-Kobe-Kyoto (Keihanshin) Japan 9 17375000 19342000 2010
Paris France   12223100 2010
Philadelphia United States   6018800 2012
Pune India   5049968 2011
Ruhr Germany   5135136 2012
Rio de Janeiro Brazil   11846530 2012
São Paulo Brazil 7 18850000 19956590 2012

Question: How many cities in the United States are included in the list of metropolitan areas by population?