Why are the Levels (editor log) from build size so big 60.6% ?

Hi,

I hope somebody can help me solve this nasty problem. My APK build size is huge because of levels

 Textures      46.1 mb     24.0% 
 Meshes        7.2 mb     3.7% 
 Animations    17.1 kb     0.0% 
 Sounds        2.8 mb     1.5% 
 Shaders       1.3 mb     0.7% 
 Other Assets  8.6 mb     4.5% 
 **Levels        116.1 mb     60.6%** 
 Scripts       1.6 mb     0.9% 
 Included DLLs 6.4 mb     3.3% 
 File headers  1.5 mb     0.8% 
 Complete size 191.6 mb     100.0%

Has anyone had the same problem? I'm using Unity 5.5.2f1. Any advice is welcomed.

Thanks in advance for any answer!