Why doesn't the Catholic Church ordain women to be deacons?

I understand that women within the Roman Catholic Church and I am guessing in the Eastern Rite Catholic Churches as well, cannot be ordained Priests. What I am wondering, is why they cannot be ordained as Permanent Deacons? Where is this written in Canon Law, and if it is, WHY? The traditional Deacon positions I can understand them not being allowed into, as it leads to the Priesthood. It would seem to me, that in this day and age of the great lack of Priests we see around our country (USA) and even around the world in many other countries, that this would an excellent way to ensure the Priests that need help would be able to get it. The Women would be doing the exact same duties and functions that Men Permanent Deacons presently do; so it is not like there are any need to change the rules regarding the positions, just the allowance to have women being able to serve as well. This seems to me to be a no-brainer for our Church, and would at the same time give women more inclusion in the Church functions. It could be open to both the laity and Religious women.