The voltage you are seeing at ambient temperature does probably not correspond to 22C as far as temperature vs voltage (according to the chart) is concerned. The only thing you can count on is the change in voltage as the temperature changes. Not the specific value at ambient. That reading is just a number. But it is a number you can start with. I would venture to guess you would get a different voltage at ambient if you tried a different resistor. To get a voltage reading where it should be at 22C, you would have to use a voltage divider.

The point is that it doesn't matter what voltage it says at 22C ambient, just consider that voltage to be 22C and go from there. A better reference would be 0C using an ice cube wrapped in plastic to get close to it. It depends on how accurate you need it to be. Also, place 0.1 microfarad capacitor across the power input to further stabilize it.