2250
Although the fertility decline in the black population in the Mississippi Delta between the late 1870 ' s and early 1930 ' s closely paralleled that of the national black population , it rose much more dramatically in the 1940 ' s and 1950 ' s to almost 1880 levels .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
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