Because the system of taxes is so different it is very difficult to compare.
It is difficult to compare because of the different nature of taxation. Most European and developing countries now use a VAT (Value Added Tax) system that taxes goods and services but is not paid by the companies involved. They collect the tax and it is accumulated down the distribution change with each step getting a credit for the tax that they paid. This means that a VAT of 7% is collected at each stage of distribution but the total tax for that product remains 7%.
It provides a big advantage for European and developing countries manufacturing base because in many plans the VAT is refunded if the product is exported.
Beyond this problem of comparing apples and oranges is the greater problem that manufacturers and businesses in the United States have to bear excessive burden because of the terrible health system that some of them have to fund which has much greater costs than other developing countries.
If you count the entire tax burden other countries pay a much higher amount per capita but they also have more discretionary money because individuals are not saddled with a puntative and costly health system.
You can read more about VAT here;
http://en.wikipedia.org/wiki/Value_added_taxOn edit you can see that the VAT in Ireland is actually higher than other countries but again when they export the government refunds the revenue collected making exports tax free.