if DX year priro to 2000, use 1907/80/90 census fields
else if DX year prior to 2010, use 2000 census fields
else use 2010 census fields.
New logic:
if DX year priro to 2000, use 1907/80/90 census fields
else if DX year prior to 2010, use 2000 census fields
else if DX year prior to 2020, use 2010 census fields
else use 2020 census fields.
Current logic:
if DX year priro to 2000, use 1907/80/90 census fields else if DX year prior to 2010, use 2000 census fields else use 2010 census fields.
New logic:
if DX year priro to 2000, use 1907/80/90 census fields else if DX year prior to 2010, use 2000 census fields else if DX year prior to 2020, use 2010 census fields else use 2020 census fields.