Surely you mean America has the best "black slaves" 
Riiiight.
Because out of 600 American athletes in the 2008 USA Olympic squad, 120 are African-American.
Now before you say something stupid like "the black slaves will win most of your medals". I would like you to keep in mind that most of our black athletes perform in track and field and basketball (male and female), and track and field is more than just 100m, 200m and 400m. The best year for US Olympic track and field was 2004 when they won 25 medals. Not all of those medals were won by blacks and in those Olympics, USA won 103 medals overall. The most by any country that year. Most of those medals won by whites. No, not hispanics, blacks, or Asian. Whitey folks.
As of this past Sunday, the USA won 12 medals. Only 1 black athlete won a medal and he didn't do it alone. He was part of the 4 x 100m freestyle relay along with Michael Phelps.