Final answer:
The statement that voter turnout for those 18 to 21 has steadily improved since 1972 is False.
Step-by-step explanation:
According to the provided information, voter turnout rates for younger age groups, including the 18 to 29 age range, have historically been lower compared to older age groups.
Although there have been some fluctuations in youth voter turnout over the years, it has generally remained lower than other age groups, except for those 65 and over. The passage also mentions that in the 2008 presidential election, voter turnout in the under-25 range briefly increased to 45 percent, but decreased to 38 percent in 2012.