The UK CAA produces an annual (IIRC) Aviation Safety Review -
CAP780 being the 2008 version.
Chapter 2, 2.6.1 indicates that the rate of reportable accidents on "large transport aircraft" at about 2.5 per million FH.
Chapter 4, Section 3.7.1 gives the rate for "small public transport aircraft" in the UK and it's about 50 per million FH.
Finally, Chapter 5, section 3.8.1 gives a reportable accident rate for "small conventional aeroplanes engaged in non-public transport operations" and it's about 180 per million FH.
So, if you flew the same number of hours on each class of aircraft, the risk is some 20 times higher on "small transport aircraft" than on large, and another 3-4 times higher on a "private aircraft". Overall, the risk per FH is about 75 times higher on a "private" plane than on an airliner.
With the caveats both in CAP780 and about statistics in general to be considered of course.