US police officer on-duty deaths

The dataset is available on Kaggle. The dataset goes back more than 150 years. I wanted to see if modern day police officers are in greater danger of being shot and killed while on-duty. However it looks as though the opposite is true:

time period               officers killed by gunfire as a % of total officers killed
pre 1850                                                       50%
1850 - 1899                                                  76.9%
1900 - 1929                                                  71.4%
1930 - 1949                                                  52.6%
1950 - 1969                                                  41.1%
1970 - 1989                                                  48%
1990 - 2008                                                  35.6%

Note that this is the percentage of officers killed by gunfire not the number of officers who have been shot. Some police officers in the US now wear body armour which may give them some protection. Two categories which have shown an increase are heart attack, up from 3.2% in the period 1850 - 1899 to 7.4% in the period 1990 - 2008. Also vehicle accidents which resulted in death, increased from 3.2% in the period 1850 - 1899 to 31.8% in the period 1990 - 2008.