Largest animal EVER to have existed

I have no idea what prompted me to google the Blue Whale this morning, but I did, and this is what I learned:

Length: up to 108 feet
Weight: 190 short tons (a short ton is a unit of weight equal to 2,000 pounds)

Blue Whales were abundant in nearly all the oceans until the beginning of the twentieth century. For over 40 years, they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 Blue Whales worldwide.

How many do you think there are today?