Congratulation to USA as the top wealth inequality of developed nation among others.
Let us look closely on data, I have summarized the data from one of the report http://publications.credit-suisse.com/tasks/render/file/index.cfm?fileid=AD783798-ED07-E8C2-4405996B5B02A32E .
 The inequality is calculated by using mean wealth divide with median wealth. If you learn math before, you should know what is mean and median and hence inequality can be calculated from those two values.

 Country                 Median    Mean         Inequality
1. United States    $ 44,977    $344,692   7.66
2. Denmark    $ 52,279    $259,816   4.97
3. Germany    $ 42,833    $185,175   4.32
4. Austria    $ 52,519    $206,002   3.92
5. Israel    $ 54,384    $176,263   3.24
6. Kuwait    $ 40,803    $119,038   2.92
7. Finland    $ 52,427    $146,733   2.80
8. Canada    $ 96,664    $270,179   2.80
9. Taiwan    $ 63,134    $172,847   2.74
10. Singapore    $101,386    $276,885   2.73
11. United Kingdom    $107,865    $288,808   2.68

Wow, the inequality of united states is  54.12 % higher than denmark. It is clearly state that citizen of usa, please ask your representtives to do and act with actions! ! !