Legendary character pieces chance increase?

Hi. I am a experienced GW2 player that has only a piece for the Disco Chomper and thats it. I have opened many Wondrous Packs of Greatness (because PopCap removed Plant Fun and Amazing Brainz packs) with NO legendary pieces. Maybe increase the chances? Because the chances are like 0.001% of getting a legendary character piece. Can you increase it by like 0.5%?