For a full description of the SCI PMachine instruction set, read one of the following:
http://wiki.scummvm.org/index.php/SCI/Specifications/SCI_virtual_machine/The_Sierra_PMachine
http://freesci.linuxgames.com/scihtml/x3140.html
The % Use column gives a rough idea of how common the instructions is. It was based on counts from the scripts of about nine SCI0 games. The most common instruction by a long way is pushi. Next comes push1, then bnt, push0, send, push, ldi, push2, jmp, lofsa. That makes up the top ten. From this we can see that of the top 10, half of them are variations of push. In fact it turns out that nearly 50% of all instructions encountered were a variation of push. The pushi instruction accounts for 25% by itself. Add in the counts for the other push instructions and it is increased to nearly 50%. The top 10 instructions account for just over 70% of all instructions encountered. The top 20 for about 85% or so, and the top 30 for nearly 95%. Some of the instructions literally appeared only once or twice across all of those games, and some instructions didn't appear at all.