Android vs. IOS statistics


Is there anybody who would share his statistics in respect to the distribution of Android/IOS?
My statistics shows 48% IOS and only 27% Android on the last month which is collected of ~1700 downloads. If I choose 3 months IOS even gets 52%.

This does not reflect the general distribution of IOS and Android smartphones, so I wonder if I can trust this, or how I could investigate this in more detail.