GROUP_CONCAT ORDER BY
You can use ORDER BY inside the GROUP_CONCAT function in this way:
SELECT li.client_id, group_concat(li.percentage ORDER BY li.views ASC) AS views,
group_concat(li.percentage ORDER BY li.percentage ASC)
FROM li GROUP BY client_id
The group_concat supports its own order by clause
http://mahmudahsan.wordpress.com/2008/08/27/mysql-the-group_concat-function/
So you should be able to write:
SELECT li.clientid, group_concat(li.views order by views) AS views,
group_concat(li.percentage order by percentage)
FROM table_views GROUP BY client_id