As I mentioned, if you were an educated person there would be no argument as to the lag of statistics. There is always a lag which is accepted in academic circles. How long do you think it takes any organization to gather data and analyze it? It takes at least 5 years to conclude that Guyanese are no longer hiding away in the US in vast numbers. Certainly the data gathering overlaps across administrations, more on the PPP side than jackass Granger PNC.
I am an educated person who works with statistics and who also knows how they are compiled. There will be the raw data which Homeland Security has and then there is the publicly available data which has to be compiled.
Druggie Homeland Security knows with a lag of a few months what % of non immigrant visas that were issued were provided to people who entered the USA. They also know whether they left. That form that you see those visitors fill in when they arrive and the airline must provide to the immigration authorities when they leave. That is their source data.
Some one whose responsibilities include immigration issues will be told what % of non immigrant visa entrants for the prior year from a specific country didn't leave the USA. Whether that information is available to you is another issue.
Druggie every first Friday of the month numbers of people who were hired from the previous month is made available. That is a considerably more complex task than finding out how many people arrived from Guyana as visitors and how many of them left after their stay in the USA.
Left to you one would think that in 2017 we would still be getting GDP or employment information from 2015!
And they don't have to "gather information" about the entry and exit of people who were issued non immigrant visas. The only group which compilation will be more difficult will be students as they are given permission to stay for a longer period, and if they do drop out of college to work Homeland Security will not get that data. But the rest they already have as the airlines have to provide that information ASAP.
And in case you don't know these E-passports allow authorities to track movements. This is why the USA forced backward countries like Guyana to get on that system or else! The I-94 form is integrated into that, so they will see that Mohan Babulall, and Sharon Ferguson entered from Guyana on a visitor's visa, but that there is no record of their departure.