Anchor New Zealand has just released a milk bottle with a black plastic layer to protect the milk from exposure to light, and thus from loss of "taste and goodness". Their chart: from their website specifically shows test results relating to vitamin B2 loss.
However, their testing is based on 2000 Lux of light, which apparently is excessive for a supermarket. Secondly, milk is unlikely to be exposed to the full brightness of light for very long unless it's perhaps a variety of milk that doesn't sell quickly.
How much vitamin B2 is lost under typical conditions (ie a high-turnover product, quickly put into the fridge at home)? Has anyone actually measured the level of vitamin B2 remaining after, say, half the milk has been consumed under normal circumstances?
I note that they clearly label their graph as "an example", which is probably intended to avoid law suits while still aiming for an emotional response from the consumer.