[albatrosstrophy]

Interestingly while the minorities have a higher birth rate compared to the majority Chinese, the ethnic breakdown remains the exact same throughout the decades. This is because Singapore's unsaid migration policy is such that the government takes in more immigrants of Chinese ethnicity to make up for the shortfall.

[MichaelZuo]

Keeping it at a fixed ratio indefinitely has a plausible legitimate reason, preventing the inevitable backroom political battles and bribery schemes by various groups seeking to tilt the immigration ratio in their favour.