You can contribute to any superannuation fund you like and as many you like. The government doesn't have something like CPF in Singapore or EPF in Malaysia. The returns could be as high as 12% per annun for some years or negative growth for a few years depending on the economy. You could choose a mix of investment portfolio e.g. international shares, bonds, property trusts etc.
But this complusory employers contributed superannuation only started something like 20years ago. Compared to Singapore and Malaysia they are playing a catch-up game in this aspect.