Read your source again. Maybe go beyond the title this time. Here is a nice excerpt: "The lifetime prevalence rates of illicit drug use among residents age 15 years or older in high-prevalence Chinese cities increased from 1.1% in 1993 to 1.6% in 1996, and the 1-year prevalence rate increased from 0.9% to 1.2% during this period [10,11]."
Now go read that again and notice that in high-prevalence regions, use is ~1-2%. Wonder what it is in the low-prevalence regions... If the US had that kind of usage statistics, every anti-drug activist in the US and I would be very happy. Even happier if use went lower.
"Last time I checked there was no data from Singapore because their government is not particularly interested in allowing independent studies to be made. There is data about their execution rate (death penalty), though. Amnesty international considers it to be amongst the highest worldwide."
First point: Singapore gives the death penalty for quite a few crimes. By itself, it is not a useful statistic. Furthermore, AI is far from a "neutral observer" on these issues. Lastly, what exactly is the problem with a high execution rate? The lack of crime?
Second point: from the CIA Factbook on Singapore: "drug abuse limited because of aggressive law enforcement efforts"