Take your most recent image (I use a .jpg image) and open it in Preview. Open the "Tools" menu and click "Show Inspector." Click the 2nd panel ("i" enclosed in circle), then click "Exif" and scroll down until you reach "Image Number." This will be your shutter activation number, assuming you've never had a shutter repair or reset (but will be correct if you had a shutter REPLACEMENT).
Never criticize a man until you walk a mile in his shoes. Then you'll be a mile away and have his shoes!