The data are from the spreadsheet of Luca Quaglia and John Tilley (see w:File:Saros-Inex_panorama.png). The time of year is calculated from the differences between the lengths of the saros and inex periods from 18 and 29 Julian years, respectively. So we use 10.82 inex number - 20.3 saros number + 5679.5 days, which spreadsheets interpret as a date.

The diagonal series are saros series, from #90 on the left to #210 on the right. The eclipses range from 160 BC at the top of saros series 91 (inex number 5) to AD 4836 at the bottom of saros series 210 (inex number 96).

The grid lines labeled "January" are around January 4 (or more accurately, Julian December 22) and the ones labeled "July" are around July 7 (more accurately, Julian June 24), corresponding to the times when the earth is at perihelion and aphelion (although they are earlier in 160 BC and later in AD 4836). In the first half of the year, eclipses are delayed and occur further east in the sky than if the eccentricity of the earth's orbit were zero, and in the second half eclipses occur early and further west in the sky. This causes the fluctuations seen in the graph.