diff --git a/stats.py b/stats.py
index 7791779..a56fcbe 100644
--- a/stats.py
+++ b/stats.py
@@ -201,8 +201,8 @@ def get_retention_graph(self: CollectionStats):
     CAST((id/1000.0 - {mw.col.sched.day_cutoff}) / 86400.0 as int)/{chunk} AS day,
     COUNT(CASE WHEN lastIvl < {config.mature_ivl} AND lastIvl > {config.mature_ivl} * -86400 THEN id ELSE NULL END) AS review_cnt_young,
     COUNT(CASE WHEN lastIvl >= {config.mature_ivl} OR lastIvl <= {config.mature_ivl} * -86400 THEN id ELSE NULL END) AS review_cnt_mature,
-    COUNT(CASE WHEN ease > 1 AND lastIvl < {config.mature_ivl} AND lastIvl > {config.mature_ivl} * -86400 THEN id ELSE NULL END) / (COUNT(CASE WHEN lastIvl < {config.mature_ivl} AND lastIvl > {config.mature_ivl} * -86400 THEN id ELSE NULL END) + 0.0001),
-    COUNT(CASE WHEN ease > 1 AND (lastIvl >= {config.mature_ivl} OR lastIvl <= {config.mature_ivl} * -86400) THEN id ELSE NULL END) / (COUNT(CASE WHEN lastIvl >= {config.mature_ivl} OR lastIvl <= {config.mature_ivl} * -86400 THEN id ELSE NULL END) + 0.0001)
+    CASE WHEN (COUNT(CASE WHEN lastIvl < {config.mature_ivl} AND lastIvl > {config.mature_ivl} * -86400 THEN id ELSE NULL END)) = 0 THEN 1 ELSE COUNT(CASE WHEN ease > 1 AND lastIvl < {config.mature_ivl} AND lastIvl > {config.mature_ivl} * -86400 THEN id ELSE NULL END) / (COUNT(CASE WHEN lastIvl < {config.mature_ivl} AND lastIvl > {config.mature_ivl} * -86400 THEN id ELSE NULL END) + 0.0001) END,
+    CASE WHEN (COUNT(CASE WHEN lastIvl >= {config.mature_ivl} OR lastIvl <= {config.mature_ivl} * -86400 THEN id ELSE NULL END)) = 0 THEN 1 ELSE COUNT(CASE WHEN ease > 1 AND (lastIvl >= {config.mature_ivl} OR lastIvl <= {config.mature_ivl} * -86400) THEN id ELSE NULL END) / (COUNT(CASE WHEN lastIvl >= {config.mature_ivl} OR lastIvl <= {config.mature_ivl} * -86400 THEN id ELSE NULL END) + 0.0001) END
     FROM revlog
     WHERE ease >= 1 AND (type = 1 OR lastIvl <= -86400 OR lastIvl >= 1)
     {lim}