Increase in Unity app size by adding google mobile ads plugin

Hi,
Before adding google mobile ads my application APK size was “26 MB” but after adding “google mobile ads” plugin the size was suddenly increased to “46 MB”. Can I know the reason what happening with this plugin or it was like this only.
Using: Unity-5.5.2P3
googleads-mobile-unity-3.5.0
Please help us.

Regards,
Raghu DS

Hi,
One more issue found, actually I ported game from “tizen” to “android”, while porting to android I added “google mobile ads” I found in editor log like this

erlier:
Textures 14.5 kb 0.1%
Meshes 0.0 kb 0.0%
Animations 0.0 kb 0.0%
Sounds 3.5 mb 31.3%
Shaders 35.3 kb 0.3%
Other Assets 414.5 kb 3.6%
Levels 243.1 kb 2.1%
Scripts 811.3 kb 7.0%
Included DLLs 6.3 mb 55.4%
File headers 30.9 kb 0.3%
Complete size 11.3 mb 100.0%

now:
Textures 169.6 mb 93.6%
Meshes 0.0 kb 0.0%
Animations 0.0 kb 0.0%
Sounds 3.5 mb 2.0%
Shaders 41.0 kb 0.0%
Other Assets 396.8 kb 0.2%
Levels 513.7 kb 0.3%
Scripts 877.6 kb 0.5%
Included DLLs 6.3 mb 3.5%
File headers 31.8 kb 0.0%
Complete size 181.2 mb 100.0%

But I not added any textures, please any help is appreciate.