I found a crazy coincidence today on the eshop. If you take the amount of people who have rated a game and multiply it by 100, you get a close to accurate number of the sales of that game to date. Some games are off by a maximum of about 25% if they have hardcore fan bases but otherwise, it's a good starting point if wondering what a game sold. I haven't seen any exceptions to the rule yet, so please feel free to share any you can fine :) 

Black ops 2 is a massive exception as the people who buy it on the U tend to play it a lot and it has some obsessive backers. Also Mario kart 8 which seems to be receiving review at a rate of more than 1/100. It seems about 1/50 people are giving mk8 a review. 

I was thinking around 1 out of 20 people rate their games/apps on digital platforms.

Surprisingly even smash brothers for Wii U is rated by about 1 in 80. 

Of course, most of the casual crowd doesn't bother. Others just don't care. Some are lazy.

I'm too busy playing the games!

Huh. Interesting. I usually try to rate my eShop games, though it might take a while before I remember, and I do them in big batches.

I only rate something if it is bad to warn others.

Aren't ratings restricted to countries?

For example WW HD has 2200 ratings on my Eshop page (by far the most).

I rate them all.

(Gotta rate them all!) :P

Huh? Mk8 has about 118,000 on my eshop so they must be different? That's really interesting, as for example, if I am in Ireland (a small country, albeit with a large gamer per capita) would the numbers be tiny then?