The national populations are growing slowly (with intercensal growth rates of 0.7 per cent and 0.4 per cent respectively) through fertility, with their respective birth rates being 24.8 and 26.5. Both countries have relatively high population density, with Samoa having 63 persons per square kilometre and Tonga 160 per square kilometre. Since Samoa is mountainous, very little potentially productive land in either country is unused.