you are right.

来源: baydad 于 2008-06-13 12:23:23 [] [旧帖] [给我悄悄话] 阅读数 : 0 (247 bytes)

Here is a quote I found on web. I was wrong.

>The average age for periods in the U.S. is 12.16 for black girls and 12.88 for whites. By age 11, 28% of black girls and 13.5% of whites menstruate. By age 12, 62% of blacks, and 35% of whites.

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