You can use the following Cost of Gas calculator to estimate how much you are spending on gasoline in an average month from this it will estimate your average cost of gas per year as well.
South Africa Population growth rate. Factbook > Countries > South Africa > Demographics. Population growth rate: 0.99% (2016 est.) Definition: The average annual percent change in the population, resulting from a surplus (or deficit) of births over deaths and the balance of migrants entering and leaving a country. The rate may be positive or negative.
According to the census held in 2012, the population of the country was estimated to be 29,195,895 - the 43rd largest in the world. But the recent estimates for 2016 indicate the total population has grown to over 31 million.