Thermal expansion coefficient from data sheets

[qsk6060]

Hi everybody
I received a data sheet of a plastic material, with the following thermal expansion values
60E-06 1/K from -30° to 30°
100E-06 1/K from 23° to 80°
I assume, that the reference temperature for these data sheets values is always 23°.
How should I use these values in Abaqus?
Some possibilities:
1-Making an average at 23° (or could be at 30°)
*EXPANSION, ZERO=23
60E-06, -30
80E-06, 23
100E-06, 80

2-Making a 'step' at 23 (or could be at 30°)
*EXPANSION, ZERO=23
60E-06, -30
60E-06, 22
100E-06, 24
100E-06, 80

Any other ideas?
Thanks a lot!