For loop increments array backwards

I am trying to do some calculations using different values stored in an array. The problem is that my array's values increase but the calculations are coming out decreasing.

Main:

public static void main(String[] args) {
    double pay, rate, deposit;
    int years;
    char yes = 'y';
    char answer;
    double[] interest = new double[15];
    interest[0] = 3.75;
    interest[1] = 4.00;
    interest[2] = 4.25;
    interest[3] = 4.50;
    interest[4] = 4.75;
    interest[5] = 5.00;
    interest[6] = 5.25;
    interest[7] = 5.50;
    interest[8] = 5.75;
    interest[9] = 6.00;
    interest[10] = 6.25;
    interest[11] = 6.50;
    interest[12] = 6.75;
    interest[13] = 7.00;
    interest[14] = 7.25;

    mortgageClass mortgagePayment = new mortgageClass();

    Scanner keyboard = new Scanner(System.in);

    System.out.print("Are you a first time buyer? ");
    answer = keyboard.next().charAt(0);
    if (answer == yes)
    {
        mortgagePayment.setRate(4.50);
    }
    else
    {
        mortgagePayment.setRate(interest[0]);
    }

    System.out.print("What is your mortage term? ");
    years = keyboard.nextInt();
    mortgagePayment.setTermYears(years);

    System.out.print("What is your amount of mortgage? ");
    pay = keyboard.nextDouble();
    mortgagePayment.setAmount(pay);

    System.out.print("What is your deposit amount? ");
    deposit = keyboard.nextDouble();
    mortgagePayment.setdepositAmt(deposit);

    System.out.printf("Your mortgage payment is %.2f ", mortgagePayment.getMonthlyPayment());
    System.out.println();

    for ( int i = 0; i < interest.length; i++ ){
        mortgagePayment.setRate(interest[i]);
        System.out.printf("Your mortgage payment is %.2f ", mortgagePayment.getMonthlyPayment());
        System.out.println();
    }
}

MortgagePayment Class

public class mortgageClass {

    private double rate;
    private double loanAmount;
    private double depositAmt;
    private int termYears;

    public void setRate(double r) {
        rate = r;
    }

    public void setAmount(double loan) {
        loanAmount = loan;
    }

    public void setTermYears(int years) {
        termYears = years;
    }

    public void setdepositAmt(double amount) {
        depositAmt = amount;
    }

    public double getMonthlyPayment() {
        rate /= 100.0;
        loanAmount = loanAmount - depositAmt;
        double monthlyRate = rate / 12.0;
        int termMonths = termYears * 12;
        double monthlyPayment = (loanAmount * monthlyRate)
                / (1 - Math.pow(1 + monthlyRate, -termMonths));
        return monthlyPayment;
    }
}

The output is decreasing

Your mortgage payment is 1309.00 
Your mortgage payment is 1220.49 //my output
Your mortgage payment is 1128.42 

When it should be increasing

Your mortgage payment is 1309.00 
Your mortgage payment is 1331.44 //Expected output
Your mortgage payment is 1354.10

Obviously the first value is assigned correctly, so why isn't the increment working?

EDIT: I have added a print statement to see if the correct values are being used and it seems like they are

  for ( int i = 0; i < interest.length; i++ ){
    mortgagePayment.setRate(interest[i]);
    //System.out.printf("Your mortgage payment is %.2f ", mortgagePayment.getMonthlyPayment());
    System.out.println(interest[i]);
    System.out.printf("Your mortgage payment is %.2f ", mortgagePayment.getMonthlyPayment());
    System.out.println();

Output:

3.75
Your mortgage payment is 1309.00 
4.0
Your mortgage payment is 1220.49 
4.25
Your mortgage payment is 1128.42 
4.5
Your mortgage payment is 1032.74 

..... I would just like to know WHY the calculations are decreasing.