Can you help me fix the average portion of my code?

Can you help me fix the average portion of my code?

When I run this code and input numbers whose sum>100 the output is correct
for the count and the sum but the average is wrong. For example; input
8,10,99... the count is 3, the sum is 117 and should return an average of
39... the actual output returned is count 3, sum 117 and average 58.5. I
have come to realize this is because the average is being done using a
count of 2 instead of 3(or always one less than it should be with
different values). Why is this? It works perfect for inputs sum<=100.
PLEASE HELP :)
public static void main(String[] args) {
//Use Main Method for gathering input
float input = 1;
// Declare variable for sum
float theSum = 0;
// Declare variable for average
float average = 0;
// Declare variable for counting the number of user inputs
int counter = 0;
/* Initialize the while loop using an input of 0 as a sentinel value
* to exit the loop*/
while (input != 0) {
// Use JOptionPane method to accept input from user
input = Float.parseFloat(
JOptionPane.showInputDialog(
null, "Please enter a number. Enter 0 to quit: "));
// Invoke sum method and pass input and summation to sum method
theSum = (sum(input, theSum));
// Invoke avg method and pass summation and counter to avg
average = (avg(theSum, counter));
// Increment the counter variable
counter++;
if (theSum > 100)
{
JOptionPane.showMessageDialog(null, "The sum of your numbers "
+ "are greater than 100!");
break;
}
}
// Invoke display method and pass summation, average, and counter
variables to it
display(theSum, average, counter);
}
public static float sum(float num1, float sum) {
//Add the user's input number to the sum variable
sum += num1;
//Return value of sum variable as new summation variable
return sum;
}
public static float avg(float num1, int num2) {
//Declare and initialize variable for average
float average = 0;
//Calculate average
average = num1 / num2;
//Return value of average variable
return average;
}
public static void display(float sum, float average, int counter) {
/* I am subtracting 1 from variable counter so as not to include the
sentinel value
* of 0 that the user had to enter to exit the input loop in the
overall count*/
// Display the count, sum, and average to the user
if (sum > 100) {
JOptionPane.showMessageDialog(null, "Count = " + (counter) + ",
Sum = " + sum + ", Average = " + average);
}
if (sum <= 100) {
JOptionPane.showMessageDialog(null, "Count = " + (counter - 1) +
", Sum = " + sum + ", Average = " + average);
}
}
}