Thats perfectly normal. It's the same case for most 2014 flagships except Z2/Z3 and other 3000 mah battery.
I lost 1% every 3 minutes (approx), therefore 20% is lost per hour, which make up as 5 hours Screen On Time with Wifi. (Depends on your usage)
With 4g, you get around 3 hours SOT and 3g...