T008 data error for US, 2006–2008

[soniayeh]

T008 https://github.com/transportenergy/database/blob/master/item/historical/scripts/T008.ipynb
data from UNECE Passenger road vehicle fleet and rate per thousand inhabitants at 31 December by vehicle category
https://w3.unece.org/PXWeb2015/pxweb/en/STAT/STAT__40-TRTRANS__03-TRRoadFleet/01_en_TRRoadTypVehR_r.px/?rxid=674effaa-3926-4d2e-9d6d-abfd7dd196b8
have obvious data error for the US after 2004 where the total veh and veh per thousand ppl dropped dramatically.

[khaeru]

FYI @transportenergy/itf-oecd colleagues

[soniayeh]

Update: According to a colleague at UNECE, this is a partly caused by a known issue, due to classifications of light trucks/big SUVs. https://www.bts.gov/content/number-us-aircraft-vehicles-vessels-and-other-conveyances. I will come back to propose a temporary fix.

[soniayeh]

For the time being, I propose a temporary fix for the US data, replacing US data in T008 with the data shown as the green line in the figures. CSV file will be sent to @hlinero separately to implement the code fix.