@sod
Not sure about the ‘raw’ data .. just looking at the graph …
As you say, salaries paid to both ‘spaces’ and ‘both’ so slow down at the 11 to 15 year mark, whereas the ‘tab’ curve just keeps going.
My inference is that with experience the only way to keep your salary increasing at the same rate is sticking with Tabs - anything else and it starts to drop off.
Conclusion - the people that pay the bills recognize that ‘Tabs’ is the way to go and reward accordingly.
I also freely accept that the data is almost certainly not connected.
‘#JustTryingToStartAConspiracyTheoryHere! 😆