Three chords are played throughout the entire song:
E |--4------4---------------------------------------------|
B |--4------6---------------------------------------------|
G |--5------5-------4-------------------------------------|
D |--4------6-------3-------------------------------------|
A |--6------4-----X-2-------------------------------------|
E |--4----------------------------------------------------|
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Source: https://tabs.ultimate-guitar.com/tab/urban_species/i_wonder_chords_1178960