Year\tQuarter\tUsage 1980\t1\t1071 1980\t2\t648 1980\t3\t480 1980\t4\t746 1981\t1\t965 1981\t2\t661 1981\t3\t501 1981\t4\t768 1982\t1\t1065 1982\t2\t667 1982\t3\t486 1982\t4\t780 1983\t1\t926 1983\t2\t618 1983\t3\t483 1983\t4\t757 1984\t1\t1047 1984\t2\t667 1984\t3\t495 1984\t4\t794 1985\t1\t1068 1985\t2\t625 1985\t3\t499 1985\t4\t850 1986\t1\t975 1986\t2\t623 1986\t3\t496 1986\t4\t728 1987\t1\t933 1987\t2\t582 1987\t3\t490 1987\t4\t708 1988\t1\t953 1988\t2\t604 1988\t3\t508 1988\t4\t708 1989\t1\t1036 1989\t2\t612 1989\t3\t503 1989\t4\t710 1990\t1\t952 1990\t2\t628 1990\t3\t534 1990\t4\t733 1991\t1\t1085 1991\t2\t692 1991\t3\t568 1991\t4\t783 1992\t1\t928 1992\t2\t655 1992\t3\t590 1992\t4\t814 1993\t1\t1018 1993\t2\t670 1993\t3\t566 1993\t4\t811 1994\t1\t962 1994\t2\t647 1994\t3\t630 1994\t4\t803 1995\t1\t1002 1995\t2\t887 1995\t3\t615 1995\t4\t828 1996\t1\t1003 1996\t2\t706