The current spot price of lumber is $0.70 per board foot and the six-month lumber futures price is $0.68 per board foot. The proportional storage cost of lumber is 4.5% per annum with continuous compounding. The interest rate is 3.5% per annum for all maturities with continuous compounding. What is the current convenience yield? (Your answer should be in decimals and accurate to three decimal places, Le. 5.4% should be written as 0.054 )