1934
Like the stock market bubble six years ago , another prime - assets bubble burst in 2006 ; this time it was the huge U.S. real estate bubble .
 six years ago, 2006, U.S.
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: date, organization, person, geographical social political, national religious political, facility, cardinal, location, work of art, law, event, product, ordinal, percent, time, quantity, money, language 
Text: {0} 
Answer:
 six years ago, 2006, U.S.