Here are the power settings as measured on an Icom IC-706 MK II (not G).
Note that each "setting" is actually a range as you rotate the knob through it.

       HF/6      2
H    100-95    19-19
9      95-85     18-16
8      80-68     16-13
7      67-53     13-10
6      52-40     10- 8
5      39-28       8- 6
4      27-20       6- 4
3      19-12       4- 2.8
2      11- 6      2.8- 1.7
1        6- 3      1.6- 1.0
L      2.5- 2.0   0.9- 0.8