dream747, I now see you come from 'Tropical Equator' so what ethnic group are you from? I am guessing you are from Asia.
Work in the past few years has shown that 'normal' BMI is different in Asians. The researchers tended to concentrate at the dividing line between 'normal' and 'overweight', which has been brought down in asian populations to perhaps around the 23. The lower limit of 'normal' is now said in asians by WHO to be around 18.5, but I suspect that if further work was done on that figure it might drop a bit too. Just an educated guess.
But anyway, just showing that what they thought was 'normal' BMI as little as 5 years ago is now considered wrong. It's really not as important as you think it is. Body fat %age and distribution is what matters in my opinion, problem with that is it's not as easy to measure accurately in a doctor's surgery as BMI, so people don't bother. That will change.....