Zero. It were three before I saw this post and checked how many there were. After close inspection they all sort of developed their own b̶i̶o̶s̶f̶e̶e̶r̶ biosphere in the bottles. So, this week I'll put Appaloosa's recipe in the fridge. My guess is that this one will not survive a week. :-)
Last year I threw away one that was 1.5 years expired.