Your firm is considering purchasing a machine with the following annual, end$-$of$-$year, book investment accounts.

Year $0$ Year $1$ Year $2$ Year $3$ Year $4$

Gross investment $ $57,000$ $ $57,000$ $ $57,000$ $ $57,000$ $ $57,000$

Less: Accumulated depreciation $014,25028,50042,75057,000$

Net investment $ $57,000$ $ $42,750$ $ $28,500$ $ $14,2500$

The machine generates, on average, $$5,600$ per year in additional net income. What is the average accounting return for this machine?