Amount of volumetric polymerization shrinkage seen in composites during curing is:
Linear shrinkage is about 0.2 to 2%.
Volumetric shrinkage is 1.7-5.7%.
Shrinkage is seen towards the centre in self cure materials and towards the light source in light cure materials. 
Reference : Nisha Garg 2ND ed Pg: 310
0.5-2%
1.7-5.7%
5.2-9.8%
12.8-17.76%