6.4 to 5.9 in 2000 but remains relatively high compared to the 1960s through the mid 1990s.
This number used to be lower in the 1970s.
mnli hypothesis: This number used to be lower in the 1970s. premise: 6.4 to 5.9 in 2000 but remains relatively high compared to the 1960s through the mid 1990s.