The following is a simple SQL statement to create a report showing the Average Length of Stay based on past checkouts.
SELECT MONTH(HISTHD.CHECKOUT) AS 'Mon',
DATENAME(MONTH,HISTHD.CHECKOUT) AS 'Month',
YEAR(HISTHD.CHECKOUT) AS 'Year',
AVG(HISTHD.NIGHTS) AS 'Avg. Stay'
FROM HISTHD
WHERE HISTHD.CHECKOUT BETWEEN {?Select Lower And Higher Date%%} AND SUBSTR(HISTHD.PREVROOM, 1,1) <> '*'
GROUP BY CHECKOUT
ORDER BY 3,1
SUBTOTAL AVG(4) ON 1 HIDEDETAIL
FORMATCOLUMN 1, HIDE=1
FORMATCOLUMN 4, COLUMNPICTURE=@N_15
FORMATCOLUMN 4, TOTALPICTURE=@N_15