Sorry, I completely answered your question wrong.
I found an article from 2015 that has some official statistics.
In 2015 from a 3-year tracking period 36,2% of former inmates committed new crimes that resulted in jail time. From a 5-year period 49,3% former inmates committed a crime that resulted in jail time. The article doesn't say what types of crimes were involved. I'm sure something is lost in translation since I'm extremely bad translating legal jargon. There are probably better and more in depth statistical data available. But to me, whatever we're doing, isn't completely working since those numbers seem pretty high to me.
Here's some more in depth official numbers but since it's in Finnish and google translator is broken, it most likely won't do you any good. Basically it says: a little less than a half of convicted criminals commit new crimes. But there's obviously more to it.