Title "New Cases of AIDS in The United States";
Variable Year;			// Year for new cases
Variable Newcases;		// Total new cases during year
Variable Childcases;		// New cases for children under 13
Parameter k1=50000;		// Initial estimate of max cases
Parameter a=5;
Parameter b=-.8;
constant baseyear=1980;
Function newcases = k1 / (1+exp(a+b*(year-baseyear)));
Plot Domain=1980,1995;
Data;
1981   188    0
1982   500   13
1983  1500   22
1984  3000   50
1985  7000  120
1986 12000  200
1987 21000  350
1988 31500  590
1989 34000  620
1990 42000  770
1991 45500  700
1992 46106  771