What are the end products in anaerobic respiration?

What are the end products in anaerobic respiration ? How much energy is released in it? Is it considered a wasteful process ?

In yeasts, ethyl alcohol and ${{CO}_{2}}$ are the end products. In some bacteria and parasitic worms, lactic acid is the end product.
Anaerobic respiration yields only about 5% energy available in food. Thus, it is considered a wasteful process.