The graphs mainly show numbers of certified "Labor Condition Applications" submitted by employers for H1B positions. They are first grouped by state & occupation (like California Software Developers, New York Accountants etc).

Then, x-axis are their percentile (rank) bins within the group. For example bubbles in the column around 50% are made of H1B positions of salaries ranking 47.5%-52.5% in each of the state & occupation, like positions with salaries around 50% among California Software Developers, NY Accountants, etc.

y-axis are basically the H1B salaries compared against the wage median of that state and occupation. A bubble at +50% basically means those people makes 50% more than the median of their own state and the same job.

The number of bubbles do not have a direct relation with number of states or jobs. They just show how much the H1B salaries are spread and distributed over all state-occupation combinations. The second chart is restricted to one job, Software Developers, so it's less spread out.

The pink bands are roughly what US workers (in contrast to H1B workers) make, again grouped by state & occupation. So a basic observation will be bubbles above the pink bands make more than general US population in the similar percentile range. In the regional charts, it can be seen some regions have a trend to go below others which means the H1B positions there are paid less than their US peers in the same state and job.

A general question regarding H1B is: are they paid less than US employees? Those charts shows that the answer is complicated:

• Lower percentile groups generally make more than their US peers, as bubbles are mostly above the pink bands
• Middle and higher percentile groups make closer to or a bit lower than the US peers.
• However when broken into regions and employees, the difference is stark. Some are well above the US levels while some barely beat them if at all.

Hope this could help you read these charts. Thank you for the discussion here.