Don't forget the trade route bonus. It's raw, but I don't know the maximum amount possible. Unless it doesn't count as direct. Anyway:
Great Library 6*0,5=3 3/350=0,00857
Spiral Minaret/University of Sankore 4*2*0,5=4 4/550=0,00727
Temple of Artemis 1+0,5=1,5 1,5/350=0,00429
Statue of Liberty 2*1=2 (engineer) 2/1500=0,00133 - worst.