Global mobile data is growing strongly. Cisco here predicted in February 2014 a 10X increase in mobile data from 2.5 Exabytes (1000GB)per month to 24EB/m by 2019. This is similar to the Ericsson projections referred to in the post below.
Total IP data is also experiencing strong growth. In June 2014 Cisco here had total world IP data in 2014 at 62EB per month growing to 132EB/m by 2018 (2.2X in four years).
From data in these Cisco reports mobile represented 4% of world data in 2014 but by 2018 this will climb to 12%.
So while they are fast growing, mobile networks are, and will remain a minority generator of world IP traffic.
The Cisco graph right also shows the growing part that WiFi has in the carriage of data. This WiFi increase will be driven by ever faster WiFi networks like those on 802.11ac providing replacement in speed and performance of wired connections for video consumption. This combined with video consumption on tablets and from dongles like Chromecast and ever increasing use of WiFi hotspots.