To be clear, this is LTE handset shipments, not LTE handset market share. The iPhone is further behind when it comes to LTE handset market share.
Apple has only had a LTE phone for 18 months. In August 2012 they were at 0%. It also doesn't show that while Q1 is usually high for iPhone shipments because they release a new phone in the fall, their Q2 & Q3 numbers go down while people wait for the next iPhone.