According to the research made possible by the participation of 400,000 women from every country, the USA has the biggest boobs by far. The research results were published in Female Health Sciences magazine. Women who had plastic surgery, who gave birth in the last year, or who were currently pregnant or breastfeeding were excluded from the research.
It was proved that women who are born in the USA have greater odds of having bigger breasts than any other countries. Asia, Africa, and east Asia have the smallest breasts. Sorry girls!
The obesity problem in the USA leading to large body parts was also considered, but it was observed that skinny women also have big breast ratios. Here's the ranking of breast sizes by countries...