I used a Fluke 289 DMM with a 470 ohm dummy load.
The voltages were the same with and without the dummy load though.
This is what I got, very similar to what you measured:
0% 0.04v
10% 1.13v
20% 2.136v
30% 3.13v
40% 4.14v
50% 5.14v
60% 6.15v
70% 7.14v
80% 8.13v
90% 9.15v
100% (99% actual) 9.97v
Looks like there is a 0.13v - 0.14v offset when the output is on. No biggie though.
