美国至7月21日6个月国债竞拍-得标利率配置百分比 81.6%，前值67.53%。

Group 1 - The core point of the article indicates that the bid-to-cover ratio for the 6-month U.S. Treasury bill auction as of July 21 reached 81.6%, an increase from the previous value of 67.53% [1]