Two fitness questions: What percentage of one's weight is lifted during a push-up?

Question 1: What is the percentage of body weight acting as resistance during a standard push-up (palms shoulder width apart, knees NOT touching the floor)? I know some of your weight is supported by your feet and not transferred to the arms, but I suspect human anatomy is consistent enough in it’s proportions to provide a range (i.e. 65-75% of total weight).

Question 2: Using the above figure: I am 6’4" and weight 218lbs. How many push-ups are required for me to burn 1 calorie?

Thanks, all.