In October 2011 I bought in ebay some kefir grains to make home made kefir.
Since they grow more and more I give them to friends and they give them further too.
Now, after 17 month I can count 25 participants.

This is the graphic on this subject.

 

And here is the graphic in large resolution:
www.flickr.com/photos/madame_ulani/8630483547

 

And here you can see how my kefir grains look like:
statigr.am/kefirpilz