Basically, the deeper the colour of the wine, the sweeter it is usually. Do they want to purge it as it is often proved so unpopular? The amount depends on the vintage (which determines to begin with the berries) as well as on the varietal arrangement. https://www.openlearning.com/u/michaelnicholson-sdl9w0/blog/RuHennessyChuynNghipCungCpCcDngSnPhmRuNgoiUyTn