Hottest by what measure? and are the year to year variations using consistent measurements? I need to see the data and not just the massaged data that you may put out for political expedience. Show the conditions at the measurement points, Rural Urban, desert . forest , in the years the measurements were taken and then you must throw out the measurements where conditions change(e.g.urbanization)
Then you must take into account the technology used if the changes make significant changes in the measurements made.
Next the systematized reporting of weather worldwide has only a 50 year history, so , without these data how can you be so certain of your statements?