<?php
$array = array(2,6,10,98,100,5,3,2,1,5,10);
print_r(array_count_values($array));
?>

Array
(
    [2] => 2
    [6] => 1
    [10] => 2
    [98] => 1
    [100] => 1
    [5] => 2
    [3] => 1
    [1] => 1
)