Given the spread, you might as well invest in a bond or some mutual funds. Assuming a 5% per annum return compounded annually, you will be up $100 in 1.64 years (that's one year and about 7 months and 21 days). Even provided that you have a baby in the oven, you are set to get $2,887.943 based on a $1,200 original investment after 18 years.
Even if you were to put it in a bank at 2% per annum, you will get $100 after about 4 years, and $1,713.90 (that's $513.90 extra) after 18 years.