If you have 3 major re- portable accident and 12 first aid cases in a year, then there must be many more near misses and your work environment needs some audit. In any work environment only 1/3 is visible / report able accidents and 2/3 are near misses, which happens every day. Any time the graph may go up. You have to observe the work environment / systems / procedures/ and behavioral pattern of each and every employee, carefully for correction. Since it is small in number the proper safety procedure can be put into place in the initial stage itself. Do not be complacence with your 1/3 cases.
Regret if i have contributed on a different opinion for your question!