Sorting data into 10% bins

Hello,

I am a research psychologist and have reaction time data from participants that I need to sort out. What I would like to do is for each participants data to be ranked from fastest to slowest, and then sort this array into 10%bins, and then get a mean of the reaction time within each 10% bin.

The problem is, that if I have 126 reaction times for each participant, 10% bins would fall every 12.6 scores, so in which 10% bin would I put RT 13? There must be a way that excel can do this instead of me literally counting out all the RTs, then working out the 10% bin criteria, and then counting every 12.6 trials and averaging them.

But is there?

I have included a small sample of the reaction time data from one participant in one condition, I have 78 ish to work through.

Thanks for you help, it will be greatly appreciated!