Data from Gallup polls over a 40-year period show how gun ownership in the United States has changed. The results are described in the table below, with the percent of Americans who own guns given in each of five decades:
Year _________________________ %
1972 ................................. 43
1982 ................................. 42
1992 ................................. 48
2002 ................................. 40
2012 ................................. 43
(a) Are the percentages reported here an example of descriptive statistics or interferential statistics?
(b) Based on the percentages given in the table, how has gun ownership in the United States changed over the past 40 years?