Get total amount of customers in WooCommerce

gistfile1.php

	function totalCustomers() {
		global $wpdb;

		$result = $wpdb->get_row("
			SELECT SUM(pm.meta_value) AS total_sales
			FROM $wpdb->posts AS p
			LEFT JOIN $wpdb->postmeta AS pm ON (p.ID = pm.post_id AND pm.meta_key = 'total_sales') 
			WHERE p.post_type = 'product'
		");

		return $result->total_sales;
	}