We are exactly 23.5% through earnings season according to my calculations. I ran an analysis on all earnings between 2000 and 2014 and figured out what dates companies report earnings. Q4 earnings releases, the ones that are being released right now, take a bit longer than those from other quarters because of the annual reports.
The chart above shows the number of companies reporting earnings on each calendar day. As of 29 Jan, on average, 1300 out of 5500 companies have reported earnings. The approximate dates of earnings season based on my analysis are below: