Actually, the US numbers are already filtered to 4-year institutions.
"The overall 6-year graduation rate for first-time, full-time undergraduate students who began seeking a bachelor’s degree at 4-year degree-granting institutions in fall 2012 was 62 percent. That is, by 2018 some 62 percent of students had completed a bachelor’s degree at the same institution where they started in 2012."
(There is some amount of skew based on this definition for students who transferred to a different institution and then completed on time, but it's hard to find numbers on students who transferred from one four-year institution to another, as opposed to all transfers who predominantly come from 2-year community colleges.)
"The overall 6-year graduation rate for first-time, full-time undergraduate students who began seeking a bachelor’s degree at 4-year degree-granting institutions in fall 2012 was 62 percent. That is, by 2018 some 62 percent of students had completed a bachelor’s degree at the same institution where they started in 2012."
https://nces.ed.gov/fastfacts/display.asp?id=40
(There is some amount of skew based on this definition for students who transferred to a different institution and then completed on time, but it's hard to find numbers on students who transferred from one four-year institution to another, as opposed to all transfers who predominantly come from 2-year community colleges.)