Manufacturers have for a long time kept ambiguous, difficult to understand, or poorly worded statistics regarding the sale of vinyl. They do not want formats to be dictated to them.
They ooccasionally bow to pressure from artists (I use that term loosely!) and occasionally consumers, but they really don't want to sell vinyl. Compaines like Acoustic Sounds or Simply Vinyl keep good records of their sales, but they are in the minority.
There really is no accurate way to know what is being sold, especially when one considers the huge 'used' market. People will even admit this if pressed, so just enjoy vinyl while you can, and prepare stories for the grand kids!