Iraq isnt missing, it has a lower population than the lowest one on here, Ukraine. Everything with a lower population isnt missing, the ones I listed above all have a higher population (with African countries excluded).
Though missing isnt really correct. because then you'd have a top 24. Colombia and Argentina wouldnt make that top 20. Also Spain would be off the list, as would south Korea and Ukraine.
long story short(er): Iran, Philippines, Burma would be in, and Spain, South Korea and Ukraine would be out if it was top 20 without African countries.
personally Spain surprised me a little, because somehow I always think it doesnt have a big population, because it is less densely populated than many other western european countries (The netherlands is approx. 400/km² italy 200/km² and spain 100/km² to give an idea)