Evapotranspiration (ET) is the sum of evaporation and plant transpiration from the Earth's land and ocean surface to the atmosphere.

What we usually estimate is the potential evapotranspiration, because the actual evapotranspiration is depended on the available hummidity.

From all the above I can't say that you can calculate such thing.

if you want a rough estimate of the potential evapotranspiration then you will need land cover maps for the period you are interested.

You need to search for "Historical data" in the climate sites.

One of the best sites that provide free and reliable historical data is the Weather Underground site. For example, I attached the meteorological data for Boston, MA from January to October 1945, which is almost 70+ years ago. Although there is no ET data listed, but you can easily calculate it by any model like PM or Hargreaves by downloading the CSV file then calculate ET by any spreadsheet software. 

You can also navigate through any city in the USA or the world, bearing in mind that the availability of historical data varies from city to city.

Best regards.

http://j.mp/2ebDjVT

Dear Zisis

Thank you for your answer. You are right, maybe it is not possible to calculate. However, my main goal is obtaining that data. I believe that the precise interpretation of satellite images could be a realistic estimation of the actual ET.

Thanks 

-Javad

Dear Mohammad

Your approach is correct and acceptable mostly for the pristine area. However, for urbanized area, the land cover change should be added to the calculation and this issue makes the procedure very difficult. I prefer to find another way, instead of calculating the ET(actual not potential) for each region by considering land cover change over the historical period of that particular zone.

Thanks for your help

Regards,

-Javad