What all of those graphs have in common is that they depict datapoints near or below zero, so they necessarily must include the zero. The only exceptions to thi

What all of those graphs have in common is that they depict datapoints near or below zero, so they necessarily must include the zero. The only exceptions to this rule are Chen and Orlik's graph, for which the data only goes down to 1, yet they decided to start at 0, and Sen's graph, which ranges from 1.8, yet he went all the way down to 1. For comparison, Feroli's data has a strictly positive range, but the graph starts at -5. Martin even went so far as to include two y-axes on the same graph, yet only one of them started at 0.