The answer is that for industry in general, we really don't know. Statistics are available for a few industries, however. In California's iron and steel foundry industry, 4.2 percent of all accidents happen when machinery is defective, or is operated under excessive stress or excessive speeds.
Typical injuries are amputation, bone fractures, lacerations, electrical shock.
Failure to lock the machine off while servicing it can result in serious and perhaps fatal injuries,especially if you are working with exposed wiring. Failure to also block moveable or potentially moveable parts of the machine is a major cause of crushing injuries. During machine cleaning, servicing or adjusting operations, the power source must be de-energized or disengaged and the moveable parts of the machine locked or blocked to prevent movement. If you have to be able to move parts of the machine in order to service it, your employer must provide you with extension tools or other means of protection, and thoroughly train you in their safe use. If the machine you are working with has lockable controls, lock them out or seal them in the off position.