The genre of thriller is basically in the niche market, this basically means that the genre dosent have a large appeal, we usually find that the genre is cut off from a large amount of the cinema population.
A factor of why thriller movies dont make as much big money of the box office is because the audience of thriller movies tends to be mainly men or teenage boys, so mainly the gender of male.
The reason behind why i think that thrillers only had 4% of the box office was because they come under other types of genresor they are appealed for a particular type of people.
Also a big factor is age, many thrillers are aged wrongly. They are meant to be aged 15 but instead are aged 18 so this leaves out a big amount of the human population.
A good thing from looking at the picture to the left is that we can see that horrors and thrillers are split evenly on the gender scale and attract both males and females.