I started tracking Euro bills on 2 July 2010 when I found out about EuroBillTracker; among the first six bills I registered on that day there was a hit right away, the only one that year. In 2011 I had six hits, only two the following year and in 2013 there were five hits, in 2014 I hit on three bills and one only in 2015 -- in 2016 I reached 1676 entered bills with 3 hits so far by mid-December; this amounts to a hit rate of 1 in 79.8 .
My wife and I are both retired, living in Berlin only temporarily so the number of bills we enter is small. They are mainly those obtained from an ATM or received as change when paying cash at a merchant, a restaurant, or at the local farmers market.
In the USA I have been tracking dollar bills since 2006 using the web site www.wheresgeorge.com so I was already familiar with the concept when I found out about the European version. My EU hit rate is still far below the one in the US which is about 1 in 11 (9.18%) out of 7093 dollar bills entered.