It comes close to possibly being the total of all submissions through 5-6 years.
It doesn't come close to that even. It omits rejected and deleted questions, but includes questions that have made it into the games while also being removed from them later on. It's not at all an accurate number.
The number does constantly grow, but from the back end of things, I can tell you that we're not at the 100,000 mark in terms of questions that have gone through the game, been rated, and stuck in the cache.