Interesting trip down memory lane.  Especially using the chained Gross Domestic Product by industry and dividing by employees to measure worker productivity.  Macro 101 is not Micro 101.

Another historical artifact, conflating cement with concrete and citing "Kapaa Quarie(s) Ameron".
In 2014, Ameron Hawaii returned to local ownership and as of  January 1, 2016, it was renamed HC&D. Calls into question the basic premise. 

Finally, inquiring minds want to know when and where was your "recent study" published?  What was the source data?  And of course was it peer reviewed?