var age_15 = [9.4, 2.35, 4.7];
			var age_16 = [9.4, 2.35, 4.7];
			var age_17 = [9.6, 2.4, 4.8];
			var age_18 = [9.8, 2.45, 4.9];
			var age_19 = [9.8, 2.45, 4.9];
			var age_20 = [10.0, 2.5, 5.0];
			var age_21 = [10.2, 2.55, 5.1];
			var age_22 = [10.4, 2.6, 5.2];
			var age_23 = [10.4, 2.6, 5.2];
			var age_24 = [10.6, 2.65, 5.3];
			var age_25 = [10.8, 2.7, 5.4];
			var age_26 = [11.0, 2.75, 5.5];
			var age_27 = [11.0, 2.75, 5.5];
			var age_28 = [11.2, 2.8, 5.6];
			var age_29 = [11.4, 2.85, 5.7];
			var age_30 = [11.6, 2.9, 5.8];
			var age_31 = [11.8, 2.95, 5.9];
			var age_32 = [12.0, 3.0, 6.0];
			var age_33 = [12.0, 3.0, 6.0];
			var age_34 = [12.2, 3.05, 6.1];
			var age_35 = [12.6, 3.15, 6.3];
			var age_36 = [12.8, 3.2, 6.4];
			var age_37 = [13.0, 3.25, 6.5];
			var age_38 = [13.4, 3.35, 6.7];
			var age_39 = [13.6, 3.4, 6.8];
			var age_40 = [14.0, 3.5, 7.0];
			var age_41 = [14.2, 3.55, 7.1];
			var age_42 = [14.4, 3.6, 7.2];
			var age_43 = [14.8, 3.7, 7.4];
			var age_44 = [14.8, 3.7, 7.4];
			var age_45 = [14.8, 3.7, 7.4];
			var age_46 = [14.8, 3.7, 7.4];
			var age_47 = [14.8, 3.7, 7.4];
			var age_48 = [14.8, 3.7, 7.4];
			var age_49 = [14.8, 3.7, 7.4];
			var age_50 = [14.8, 3.7, 7.4];
			var age_51 = [14.8, 3.7, 7.4];
			var age_52 = [14.8, 3.7, 7.4];
			var age_53 = [14.8, 3.7, 7.4];
			var age_54 = [14.8, 3.7, 7.4];
			var age_55 = [14.8, 3.7, 7.4];
			var age_56 = [14.8, 3.7, 7.4];
			var age_57 = [14.8, 3.7, 7.4];
			var age_58 = [14.8, 3.7, 7.4];
			var age_59 = [14.8, 3.7, 7.4];
			var age_60 = [14.8, 3.7, 7.4];
			var age_61 = [14.8, 3.7, 7.4];
			var age_62 = [14.8, 3.7, 7.4];
			var age_63 = [14.8, 3.7, 7.4];
			
			
			function checkKey(e) {
				var char = (e.which) ? e.which : e.keyCode;
			
				if (char > 31 && (char < 48 || char > 57))
					return false;
			
				return true;
			}
			
			function calculate() {
				
				var age = document.getElementById('age').value;
				var grosspay = document.getElementById('gross_pay').value;
				var overpaid = document.getElementById('over_paid');		
				var tiers = eval('age_' + age);	
			
				var pay1 = (grosspay >= 13500) ? 13500 - 4680 : 13500;
				var pay2 = (grosspay >= 31100) ? 31100 - 13500 : grosspay - 13500;
				var pay3 = (grosspay >= 40400) ? 40400 - 31100 : grosspay - 31100;
				
				var rebate1 = pay1 * (tiers[0] / 100);
				var rebate2 =  (pay2 > 0 ) ? pay2 * (tiers[1] / 100) : 0;
				var rebate3 =  (pay3 > 0) ? pay3 * (tiers[2] / 100) : 0;
			
				var totalRebate = rebate1 + rebate2 + rebate3;
			
				overpaid.value = totalRebate;
			
			
			}