you could say
That 419 scammers are targeting the big rich, western decadent societies that have people with lots of disposable income, relatively speaking..
Or you could say that we are an easy target with an uneducated populace that fall for these things. (my favourite)
Or you could say the people falling for these tend to be old because our health systems are so good we have an older class to be targeted.
Or you could say that English is the most common business language so target that first and then spread out wards, you are more likely to get a response.
Or you could say that our economy strength puts us in the more likely to give "a larger return" category.
Or you could say that our limp wristed and victorian infrastructure (BT, Ofcom, the 21CN) and "bygone era" ideology has meant we are chasing the world in sorting out the 419 scammers and spam in general.