Familes that are still together

wife and I married 16 years - 2 kids
my parents and gparents were together unto death (my dad was adopted - his adopted father died in WW2 - when his adopted mom remarried they were together for the duration)
my sister's marriage lasted somewhere between 10-15 years, no kids)

wife's mom and biological dad split early (like she was 2 or something)
mom and 2nd dad were probably heading for divorce when he died in motorcycle accident when she was about 15)

i know national avg is supposed to be around 50%, but my unscientific data says about 75% of my students (20ish years) have mom/dad intact families