Complex sentence: To date, however, only twelve states have ratified it and it is unlikely that the amendment will ever be adopted--the most recent state to approve it was Kentucky in June of 1792 (Kentucky's initial month of statehood).
Split into simpler sentences: To date, only twelve states have ratified the amendment, and it is unlikely that the amendment will ever be approved. The most recent state to do so was Kentucky in June of 1792 (Kentucky's initial month of statehood).