Out-of-wedlock births are soaring rapidly in the West, reflecting an increasingly liberal attitude towards family formation. But in the East, where the traditional family structure is still widely valued as the bedrock of society, the percentage of births outside marriage remains low. SMU Assistant Professor of Sociology Bussarawan Puk Teerawichitchainan commented, "Non-marital child-bearing is much less common in the East because it's still stigmatised." A study by the Population Reference Bureau (PRB) – which tracked the trend from 1960 onwards – showed a rapid rise in out-of-wedlock births in Australia, New Zealand, the United States and almost all of Europe, with the exception of a few countries like Belarus, Greece and Russia.