How to get total count for each star rating?

You can use the function get_rating_count() by specifying on each call the value needed. For example :

global $product;

$rating_1 = $product->get_rating_count(1);
$rating_2 = $product->get_rating_count(2);
$rating_3 = $product->get_rating_count(3);
$rating_4 = $product->get_rating_count(4);
$rating_5 = $product->get_rating_count(5);

You can read more about the function