A timeout in online chess is caused by a member not making a move in their game within the allotted time. (meaning your run out of time)

It shows on the right side of your online games page underneath your ratings

Yours currently shows as

All Games

Use the Help link at the top of the page.  You will find helpful things.  Like this: http://support.chess.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=683

It appears that out f 106 of your Online games, you have lost due to inactivity 16 times—thus your 15%.

Play more Online games, stop losing on time, and the 15% will drop.

As far as I know, "Time Out" is when in Online games you lose because of not making your move before time is up.

I would set games to 14 days and try to make each of your moves within 14 days.