As far as I understood the website, I would need to pay for a 1 year subscription to get current values and on google the most current value I found was for 2015 in an engineering forum.
For your student work 2015 should be OK too. It actually focus es on the method of using the value. It takes atleast 3-5 years to get these values free. In the mean time you have to pay for it. It used by consultants who can afford to pay the subscription.