In the chart on the left red bars depict terms that the president did not complete, while green bars depict terms in which there was a significant threat to the president’s completion of the term (a serious illness, impeachment, or assassination attempt.)
The chart shows that for the last 40 years (going back to 1976) presidents have completed their terms. We had two scares (the assassination of Reagan and the Clinton impeachment) but no one actually left office early.
But in the 40 years before that (1936-1976) one president died in office, another was assassinated, while a third resigned. Further, Eisenhower, Kennedy, and Johnson all faced serious health problems in office.
In the forty years before that (1896 to 1936) one president was assassinated and another died from an illness. Woodrow Wilson was incapacitated for several months. A Constitutional crisis was averted by legerdemain on the part of the First Lady and the President’s personal physician.
And the 40 years before that (1856-1896) two Presidents were assassinated. In addition Andrew Johnson was impeached and Chester Alan Arthur was very ill in office.
Now back to 1816-1856 two Presidents died in office from illness.
The point of this little history lesson is that we are living in a period of robust presidential health, unprecedented since the establishment of the Republic.