I honestly don't know. Let's think...
I've killed almost my complete first collection. I was growing some trees on a small balcony in Amsterdam. I knew the environment wasn't really good... and yeah, it wasn't. A few survived.
I killed almost my complete second collection. We purchased a house, I got a big garden, but the house was a bit small so we extended it.I did a lot of the interior work myself and, having young kids as well, I just didn't have the time to care for my trees.
I picked up the hobby again some 7 years ago (after I took my Juniper to the club, and was told it was a great tree, that would be ready for the Noelanders trophy in 3 years. That same tree has been dying for four years now. Still not completely dead).
Seedlings... killed quite a few of 'm.
So... errmm... more than 30.
Things did start to go much better, last couple of years. Hardly any losses after winter. Did Loose a few plants this year due to the extreme heat (and underestimating that heat).