With the end of the draft, going to an all volunteer force, you're going to have more presidents than not without military service. Trump and Obama, the two most recent had none. G.W. Bush was in the Texas National Guard, Bill Clinton had none. Then you have to go back to FDR to find the next president without military service. It should be noted FDR was the Assistant secretary of the Navy during WWI and attempted to resign his federal post to join the military, but his resignation wasn't accept. Hoover, Coolidge, Harding, Wilson also had none. Further back is ancient history.
Only two of the current Democratic presidential candidates have had military experience, Mayor Pete Buttigieg of South Bend, Indiana had a seven month deployment in Afghanistan and continues to serve as a lieutenant in the United States Navy Reserve.
Tulsi Gabbard, congresswoman for Hawaii’s second district, is the only other veteran. Gabbard served in a field medical unit of the Hawaii Army National Guard in Iraq and was also deployed in Kuwait.
Bottom line, unless Gabbard or Buttigieg wins the Democratic nomination and the general election, we're going to have another president without military service or experience.