finding avg/min/max for a dataset using mapreduce - mapreduce

Question

i am trying to write a mapreduce sample practice program where in my data set is somthing like this
its about salaries of people in every year in a country/city/state
place year salary($)
america 2014 60,000
france 2010 40,000
india 2012 20,000
australia 2001 50,000
america 2014 65,000
i want output something like this
place year avg min max
america 2014 625000 600000 650000
france 2010 400000 400000 400000
please guide me how can i write a mapreduce program/ any sample program which is already handled such case.
thanks in advance :)
i have tried mapper part
public static class Map extends Mapper{
public void map(LongWritable key, Text value,
Context context)
throws IOException,InterruptedException {
String year=null;
String country =null;
String amount=null;
// this will work even if we receive more than 1 line
Scanner scanner = new Scanner(value.toString());
String line;
String[] tokens;
while (scanner.hasNext()) {
line = scanner.nextLine();
tokens = line.split("\\s+");
country = tokens[0];
year = tokens[1];
amount = (tokens[2]);
context.write(new Text(country), new Text(year));
context.write(new Text(year), new Text(amount));
}
}
}