Shell Programming and Scripting

awk 'NR==1; NR>1{A[$2]+=$3; C[$2]++} END{for (i in A) print i,A[i]/C[i]}' OFMT='%.2f'  file

awk '                
  NR==1                                # If it is the first line in the file it is the header, perform the default action, i.e. print the line { print $0 }
  NR>1{                                # For Any subsequent line, for every line :
    A[$2]+=$3                          # Create an element in associative array A with the second field as the index and the third field to its value..
    C[$2]++                            # Increase the counter in associative array C for field $2 
  } 
  END{                                 # When all lines are processed
    for (i in A) print i,A[i]/C[i]     # Run throught the array elements and print the index and the total value / divided by the number of occurences , using OFMT for the format.
  }
' OFMT='%.2f' file                    # set the format to 2 decimals and specify the file name.