Finish new stats.

src/mbase-query.scm

@@ -47,6 +47,13 @@
   (define (members-base-oldest-month mb)
     (make-cal-month 2015 1))
 
+  (define (members-average-age mrs)
+    (let* ((ages (map brmember-age mrs))
+	   (valid (filter (lambda (x) x) ages))
+	   (num (length valid))
+	   (sum (foldl + 0 valid)))
+      (exact->inexact (/ sum num))))
+
   ;; Returns dictionary with statistics about the members base.
   (define (mbase-info mb-arg)
     (let* ((members (find-members-by-predicate mb-arg brmember-usable?))
@@ -81,10 +88,10 @@
 				   (map (lambda (v)
 					  (min 0 v))
 					mbals))))
-	   ;; debts of fees
-	   ;; add average age of active members
+	   (di13 (ldict-set di12 'age
+			    (members-average-age active-members)))
 	   )
-      di12))
+      di13))
 
   ;; Returns a list two lists: keys, data.
   ;; Each data record contains values for all keys.
@@ -93,6 +100,7 @@
 	   '(month
 	     total active suspended students destroyed invalid
 	     expected balance advance debt
+	     age
 	     )))
       (let mloop ((data '())
 		  (month (members-base-oldest-month mb)))