How does the market structure look like?(number of entities

How does the market structure look like?(number of entities and contribution to GDP)
How does the market share structure look like?Look for the information which is available about the different market shares.

How does the market structure look like?
Yum...  Market structure... Do you mean the Monopolistic competition, Oligopoly, Duopoly... Well, abysmal question when referring the GDP contribution. 
For your consideration.
①Monopolistic competition: competitive environment, numerous entities, less market share, more differentiated products.
②Oligopoly: less competition, pricing is dominated by fewer entities (usually 2-4).
③Duopoly: a special case of an oligopoly with two firms.
④Monopoly: one entity, no competition
⑤Natural monopoly: quoted from wiki: "a monopoly in which economies of scale cause efficiency to increase continuously with the size of the firm. A firm is a natural monopoly if it is able to serve the entire market demand at a lower cost than any combination of two or more smaller, more specialized firms.".
⑥Perfect competition: unlimited entities, more similar products with the most cut-throat competition.
Competition will foster the market to expand more rapidly. So the more competitive the market is, the more it will contribute to the GDP.
How does the market share structure look like?
Pictures attached here.
BTW, I guess you guy are studying overseas? Major in Economics...