$.ajax({
url: "assets/ajax.php",
dataType: "json",
success: function(data){
console.log(data);
}
});
({"cnt_pay_s":"1 523","cnt_pay_z":"22 924","cnt_pay_a":"29 587","cnt_z":"227 450","cnt_s":"7 456","sum_z":"2 544 060 000","sum_s":"1 723 330 000"})
data.slice(1, -1)
, например.