Male Female Ratio...

While browsing the internet on male-female ratios across the world, I came across this website where they have listed male-female ratios among people of various racial origins in USA.

None of the ratio's have more than 10% difference. In fact many of them have less than 5% difference in ratio. I am positive that the ratio will be similar across the world. In fact, I am equally positive that it will be a less than 10% difference for all such species in the world. (Is there any species where the ratio is skewed?)

Is the only scientific explanation for this, probability?

Katrina

Watching CNN, Katrina refugees were heading to Houston for shelter. The CNN reporter said that the city of Houston was making a "great" "sacrifice" in letting people in from the neighbouring states and "allowing" them to stay in one of it's superdomes.