Calculate Coin Supply at any given time The total number of coins mined/available should be readable from the blockchain. 
But is also possible to calculate the number of coins which were/will be available at any given time?
Yes. Thats possible. I wrote a python program that returns the supply at a given block (works with future supply, too):

#!/usr/bin/env python
# -*- coding: utf8 -*-

def btcSupplyAtBlock(b):
  reward = 50
  supply = 0
  y = 210000 # reward changes all y blocks
  while b&gt;y:
    supply = supply + y * reward
    reward = reward / 2.0
    b = b - y
  supply = supply + b * reward
  return supply

block = 514227 # you want the supply after which block?
print(btcSupplyAtBlock(block))



supply at block 0: 0
supply at block 100,000: 5,000,000
supply at block 514,227: 16,927,837.5
supply at block 1,000,000: 20,187,500