Suppose that an investor opens an account by investing $1000. At the beginning of each of the next four years, he deposits an additional $1000 each year, and then he liquidates the account at the end of the total five-year period. Suppose that the yearly returns in this account, beginning in year 1 are as follows: 12%, 5%, 8%, -7%, and -14%. Calculate the investor's dollar-weighted average return for this five-year period.