Ridzwan,
First of all, the statistics is a rough projection.
Second, most of these immigrants from China and India form most of
the labour in our construction industry.
Though what you have mentioned that Malays has declined in terms of
population, this also affected the other races maybe due to higher
standards of living compared from 1990 to the current year.
(Correct me if i am wrong on this) Furthermore, from what i heard
from rumours is that Malays in Singapore gets better subsidies for
eductation, housing, etc.
As i do not wanna see this thread to be flamed by racism comments
and such. Our forefathers has come so far to make this country our
own, so let's not pull other countries politics into our own. We
share and have tolerance one another beliefs and culture. Only
people with shallow mindset and value systems will try to destroy
this harmony. 
