Trading Skill Proficiency

When you buy a certain goods, you will earn trading skill proficiency related to the goods and your proficiency of the related trading skill will up. . For example, if you have Livestock Trading skill and you buy a chicken(which is livestock), then you will earn certain quantity proficiency of Livestock Trading. To be more accurate you will get 2 proficiency for every 3 goods you have been bought.
 * Maximum proficiency you can get is 40 per transaction. This is mean you will get 40 Livestock Trading proficiency no mather you are buying 60 chicken or 100 chicken. To get maximum benefit, you need to split transaction. This mean you must buy 60 chicken and then close transaction and buy again 40 chicken rather then buy 100 chicken at once. By this method you will earn 40 + 26 = 66 proficiency compare to 40 if you buy at once.
 * When you reach certain amount of proficiency of specific skill, that skill level will be increase.