http://catholicharboroffaithandmorals.com/Most%20Precious%20Blood%20popup.html
Because the Precious Blood goes hand in hand with the Sacred Heart.
In reparation for the sacrilege committed in Oklahoma.
"Thus Jesus shed His precious blood seven times, and the price of these seven sheddings of blood is found in the seven Sacraments, by which we are cleansed from sin and sanctified. These seven sheddings of blood remind us also of the three Theological and the four Cardinal virtues; also of the seven virtues opposed to the seven deadly or capital sins, which are infused into us by baptism; also of the seven gifts of the Holy Ghost, which we receive in confirmation, and finally of the seven days of the week, which we should dedicate to the service of God. The covenant between God and the Israelites was sealed with blood. The new covenant was sealed with the precious blood of Jesus Christ. The covenant between God and men is sealed again as many times as the Holy Sacrifice of the Mass is offered to God. Assist, whenever you can, at the tremendous Sacrifice of the Mass, and frequently receive holy communion".