yeah, you almost don't want to know, because it's sort of like "hey, I COULD have had 25BTC" 
- snip -although in practice, when you mine you are trying to find a different block vs what you'd search soloing,
^^This^^
When you mine in a pool, the pool creates the block header that you are hashing. That block includes a coinbase transaction that pays the block reward to the pool..
If you were solo mining, your block would include a coinbase transaction that pays the block reward to you. This would result in a completely different merkle root in the block header. Therefore, you would be generating completely different hashes while solo mining, and the nonce that you stumbled upon in the pool would not have worked for your solo mining attempt. In other words, you only found the block because you were mining in the pool. There is no way to know if you would have found a block solo mining.