The following code should be what you want.
count = 0
total = 0
while True:
x = raw_input('Enter number: ')
if(x.lower() == "done"):
break
else:
try:
x=int(x)
total = total + x
count = count + 1
average = total / count
except:
print("That is not an integer. Please try again.")
print total, count, average
or in Python 3
count = 0
total = 0
while True:
x = input('Enter number: ')
if(x.lower() == "done"):
break
else:
try:
x=int(x)
total = total + x
count = count + 1
average = total / count
except:
print("That is not an integer. Please try again.")
print(total, count, average)