very interesting research. I would opine that the cause is a combination of most or all of the causes you listed, altogether magnifying the data you gathered. personally, i think, on the one extreme, regulation has had a material impact at least on the US, and yet, to the other extreme, lack of regulation and the presence and seeming increase in graft and corruption also has something to do with it. Globally, politically, we have seen a trend toward soft socialism and/or statism in many developed countries including the US. We know these trends to have a quelling effect on free markets. These are observations i feel i have noticed in recent years