Whisky, that has been in these barrels since before I was even born.
This picture is from a distillery tour of the Tomatin distillery in Scotland earlier this year. These casks can loose up to 2% of its water and alcohol content per year due to evaporation from the wooden barrels.
A twelve year old scotch would loose up to 24% of its liquid by the time it is ready for consumption. This diminution is called the “angel’s share”. That does not include the devils cut (liquid the oak soaks up, which can be around 5% of the total liquid).
Back when people first started ageing spirits in wooden casks they where puzzled by this loss in liquidity. Since they could not explain it to them, they believed it was consumed by angels, hence its called the angel’s share.